Polypeptide compounds for inhibiting angiogenesis and tumor growth

ABSTRACT

In certain embodiments, this present invention provides polypeptide compositions, and methods for inhibiting Ephrin B2 or EphB4 activity. In other embodiments, the present invention provides methods and compositions for treating cancer or for treating angiogenesis-associated diseases.

RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalApplication No. 60/454,300 filed Mar. 12, 2003 and U.S. ProvisionalApplication No. 60/454,432 filed Mar. 12, 2003. The entire teachings ofthe referenced Provisional Applications are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

Angiogenesis, the development of new blood vessels from the endotheliumof a preexisting vasculature, is a critical process in the growth,progression, and metastasis of solid tumors within the host. Duringphysiologically normal angiogenesis, the autocrine, paracrine, andamphicrine interactions of the vascular endothelium with its surroundingstromal components are tightly regulated both spatially and temporally.Additionally, the levels and activities of proangiogenic and angiostaticcytokines and growth factors are maintained in balance. In contrast, thepathological angiogenesis necessary for active tumor growth is sustainedand persistent, representing a dysregulation of the normal angiogenicsystem. Solid and hematopoietic tumor types are particularly associatedwith a high level of abnormal angiogenesis.

It is generally thought that the development of tumor consists ofsequential, and interrelated steps that lead to the generation of anautonomous clone with aggressive growth potential. These steps includesustained growth and unlimited self-renewal. Cell populations in a tumorare generally characterized by growth signal self-sufficiency, decreasedsensitivity to growth suppressive signals, and resistance to apoptosis.Genetic or cytogenetic events that initiate aberrant growth sustaincells in a prolonged “ready” state by preventing apoptosis.

It is a goal of the present disclosure to provide agents and therapeutictreatments for inhibiting angiogenesis and tumor growth.

SUMMARY OF THE INVENTION

In certain aspects, the disclosure provides polypeptide agents thatinhibit EphB4 or EphrinB2 mediated functions, including monomeric ligandbinding portions of the EphB4 and EphrinB2 proteins and antibodies thatbind to and affect EphB4 or EphrinB2 in particular ways. As demonstratedherein, EphB4 and EphrinB2 participate in various disease states,including cancers and diseases related to unwanted or excessiveangiogenesis. Accordingly, certain polypeptide agents disclosed hereinmay be used to treat such diseases. In further aspects, the disclosurerelates to the discovery that EphB4 and/or EphrinB2 are expressed, oftenat high levels, in a variety of tumors. Therefore, polypeptide agentsthat downregulate EphB4 or EphrinB2 function may affect tumors by adirect effect on the tumor cells as well as an indirect effect on theangiogenic processes recruited by the tumor. In certain embodiments, thedisclosure provides the identity of tumor types particularly suited totreatment with an agent that downregulates EphB4 or EphrinB2 function.

In certain aspects, the disclosure provides soluble EpbB4 polypeptidescomprising an amino acid sequence of an extracellular domain of an EphB4protein. The soluble EphB4 polypeptides bind specifically to an EphrinB2polypeptide. The term “soluble” is used merely to indicate that thesepolypeptides do not contain a transmembrane domain or a portion of atransmembrane domain sufficient to compromise the solubility of thepolypeptide in a physiological salt solution. Soluble polypeptides arepreferably prepared as monomers that compete with EphB4 for binding toligand such as EphrinB2 and inhibit the signaling that results fromEphB4 activation. Optionally, a soluble polypeptide may be prepared in amultimeric form, by, for example, expressing as an Fc fusion protein orfusion with another multimerization domain. Such multimeric forms mayhave complex activities, having agonistic or antagonistic effectsdepending on the context. In certain embodiments the soluble EphB4polypeptide comprises a globular domain of an EphB4 protein. A solubleEphB4 polypeptide may comprise a sequence at least 90% identical toresidues 1-522 of the amino acid sequence defined by FIG. 65. A solubleEphB4 polypeptide may comprise a sequence at least 90% identical toresidues 1-412 of the amino acid sequence defined by FIG. 65. A solubleEphB4 polypeptide may comprise a sequence at least 90% identical toresidues 1-312 of the amino acid sequence defined by FIG. 65. A solubleEphB4 polypeptide may comprise a sequence as set forth in FIG. 1 or 2.In certain embodiments, the soluble EphB4 polypeptide may inhibit theinteraction between Ephrin B2 and EphB4. The soluble EphB4 polypeptidemay inhibit clustering of or phosphorylation of Ephrin B2 or EphB4.Phosphorylation of EphrinB2 or EphB4 is generally considered to be oneof the initial events in triggering intracellular signaling pathwaysregulated by these proteins. As noted above, the soluble EphB4polypeptide may be prepared as a monomeric or multimeric fusion protein.The soluble polypeptide may include one or more modified amino acids.Such amino acids may contribute to desirable properties, such asincreased resistance to protease digestion.

In certain aspects, the disclosure provides soluble EphrinB2polypeptides comprising an amino acid sequence of an extracellulardomain of an EphrinB2 protein. The soluble EphrinB2 polypeptides bindspecifically to an EphB4 polypeptide. The term “soluble” is used merelyto indicate that these polypeptides do not contain a transmembranedomain or a portion of a transmembrane domain sufficient to compromisethe solubility of the polypeptide in a physiological salt solution.Soluble polypeptides are preferably prepared as monomers that competewith EphrinB2 for binding to ligand such as EphB4 and inhibit thesignaling that results from EphrinB2 activation. Optionally, a solublepolypeptide may be prepared in a multimeric form, by, for example,expressing as an Fc fusion protein or fusion with anothermultimerization domain. Such multimeric forms may have complexactivities, having agonistic or antagonistic effects depending on thecontext. A soluble EphrinB2 polypeptide may comprise residues 1-225 ofthe amino acid sequence defined by FIG. 66. A soluble EphrinB2polypeptide may comprise a sequence defined by FIG. 3. In certainembodiments, the soluble EphrinB2 polypeptide may inhibit theinteraction between Ephrin B2 and EphB4. The soluble EphrinB2polypeptide may inhibit clustering of or phosphorylation of EphrinB2 orEphB4. As noted above, the soluble EphrinB2 polypeptide may be preparedas a monomeric or multimeric fusion protein. The soluble polypeptide mayinclude one or more modified amino acids. Such amino acids maycontribute to desirable properties, such as increased resistance toprotease digestion.

In certain aspects, the disclosure provides antagonist antibodies forEphB4 and EphrinB2. An antibody may be designed to bind to anextracellular domain of an EphB4 protein and inhibit an activity of theEphB4. An antibody may be designed to bind to an extracellular domain ofan Ephrin B2 protein and inhibit an activity of the Ephrin B2. Anantibody may be designed to inhibit the interaction between Ephrin B2and EphB4. An antagonist antibody will generally affect Eph and/orEphrin signaling. For example, an antibody may inhibit clustering orphosphorylation of Ephrin B2 or EphB4. An antagonist antibody may beessentially any polypeptide comprising a variable portion of anantibody, including, for example, monoclonal and polyclonal antibodies,single chain antibodies, diabodies, minibodies, etc.

In certain aspects, the disclosure provides pharmaceutical formulationscomprising a polypeptide reagent and a pharmaceutically acceptablecarrier. The polypeptide reagent may be any disclosed herein, including,for example, soluble EphB4 or EphrinB2 polypeptides and antagonistantibodies. Additional formulations include cosmetic compositions anddiagnostic kits.

In certain aspects the disclosure provides methods of inhibitingsignaling through Ephrin B2/EphB4 pathway in a cell. A method maycomprise contacting the cell with an effective amount of a polypeptideagent, such as (a) a soluble polypeptide comprising an amino acidsequence of an extracellular domain of an EphB4 protein, wherein theEphB4 polypeptide is a monomer and binds specifically to an Ephrin B2polypeptide; (b) a soluble polypeptide comprising an amino acid sequenceof an extracellular domain of an Ephrin B2 protein, wherein the solubleEphrin B2 polypeptide is a monomer and binds with high affinity to anEphB4 polypeptide; (c) an antibody which binds to an extracellulardomain of an EphB4 protein and inhibits an activity of the EpbB4; or (d)an antibody which binds to an extracellular domain of an Ephrin B2protein and inhibits an activity of the Ephrin B2.

In certain aspects the disclosure provides methods for reducing thegrowth rate of a tumor, comprising administering an amount of apolypeptide agent sufficient to reduce the growth rate of the tumor,wherein the polypeptide agent is selected from the group consisting of:(a) a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; (b) asoluble polypeptide comprising an amino acid sequence of anextracellular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide; (c) an antibody which binds to an extracellular domain ofan EphB4 protein and inhibits an activity of the EphB4; and (d) anantibody which binds to an extracellular domain of an Ephrin B2 proteinand inhibits an activity of the Ephrin B2. Optionally, the tumorcomprises cells expressing a higher level of EphB4 and/or EphrinB2 thannoncancerous cells of a comparable tissue.

In certain aspects, the disclosure provides methods for treating apatient suffering from a cancer. A method may comprise administering tothe patient a polypeptide agent selected from the group consisting of:(a) a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; (b) asoluble polypeptide comprising an amino acid sequence of anextracellular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide; (c) an antibody which binds to an extracellular domain ofan EphB4 protein and inhibits an activity of the EphB4; and (d) anantibody which binds to an extracellular domain of an Ephrin B2 proteinand inhibits an activity of the Ephrin B2. Optionally, the cancercomprises cancer cells expressing EphrinB2 and/or EphB4 at a higherlevel than noncancerous cells of a comparable tissue. The cancer may bea metastatic cancer. The cancer may be selected from the groupconsisting of colon carcinoma, breast tumor, mesothelioma, prostatetumor, squamous cell carcinoma, Kaposi sarcoma, and leukemia.Optionally, the cancer is an angiogenesis-dependent cancer or anangiogenesis independent cancer. The polypeptide agent employed mayinhibit clustering or phosphorylation of Ephrin B2 or EphB4. Apolypeptide agent may be co-administered with one or more additionalanti-cancer chemotherapeutic agents that inhibit cancer cells in anadditive or synergistic manner with the polypeptide agent.

In certain aspects, the disclosure provides methods of inhibitingangiogenesis. A method may comprise contacting a cell with an amount ofa polypeptide agent sufficient to inhibit angiogenesis, wherein thepolypeptide agent is selected from the group consisting of: (a) asoluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; (b) asoluble polypeptide comprising an amino acid sequence of anextracellular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide; (c) an antibody which binds to an extracellular domain ofan EphB4 protein and inhibits an activity of the EphB4; and (d) anantibody which binds to an extracellular domain of an Ephrin B2 proteinand inhibits an activity of the Ephrin B2.

In certain aspects, the disclosure provides methods for treating apatient suffering from an angiogenesis-associated disease, comprisingadministering to the patient a polypeptide agent selected from the groupconsisting of: (a) a soluble polypeptide comprising an amino acidsequence of an extracellular domain of an EphB4 protein, wherein theEphB4 polypeptide is a monomer and binds specifically to an Ephrin B2polypeptide; (b) a soluble polypeptide comprising an amino acid sequenceof an extracellular domain of an Ephrin B2 protein, wherein the solubleEphrin B2 polypeptide is a monomer and binds with high affinity to anEphB4 polypeptide; (c) an antibody which binds to an extracellulardomain of an EphB4 protein and inhibits an activity of the EphB4; and(d) an antibody which binds to an extracellular domain of an Ephrin B2protein and inhibits an activity of the Ephrin B2. The solublepolypeptide may be formulated with a pharmaceutically acceptablecarrier. An angiogenesis related disease or unwanted angiogenesisrelated process may be selected from the group consisting ofangiogenesis-dependent cancer, benign tumors, inflammatory disorders,chronic articular rheumatism and psoriasis, ocular angiogenic diseases,Osler-Webber Syndrome, myocardial angiogenesis, plaqueneovascularization, telangiectasia, hemophiliac joints, angiofibroma,wound granulation, wound healing, telangiectasia psoriasis scleroderma,pyogenic granuloma, cororany collaterals, ischemic limb angiogenesis,rubeosis, arthritis, diabetic neovascularization, fractures,vasculogenesis, and hematopoiesis. An polypeptide agent may beco-administered with at least one additional anti-angiogenesis agentthat inhibits angiogenesis in an additive or synergistic manner with thesoluble polypeptide.

In certain aspects, the disclosure provides for the use of a polypeptideagent in the manufacture of medicament for the treatment of cancer or anangiogenesis related disorder, wherein the polypeptide agent is selectedfrom the group consisting of: (a) a soluble polypeptide comprising anamino acid sequence of an extracellular domain of an EphB4 protein,wherein the EphB4 polypeptide is a monomer and binds specifically to anEphrin B2 polypeptide; (b) a soluble polypeptide comprising an aminoacid sequence of an extracellular domain of an Ephrin B2 protein,wherein the soluble Ephrin B2 polypeptide is a monomer and binds withhigh affinity to an EphB4 polypeptide; (c) an antibody which binds to anextracellular domain of an EphB4 protein and inhibits an activity of theEphB4; and (d) an antibody which binds to an extracellular domain of anEphrin B2 protein and inhibits an activity of the Ephrin B2.

In certain aspects, the disclosure provides methods for for treating apatient suffering from a cancer, comprising: (a) identifying in thepatient a tumor having a plurality of cancer cells that express EphB4and/or EphrinB2; and (b) administering to the patient a polypeptideagent selected from the group consisting of: (i) a soluble polypeptidecomprising an amino acid sequence of an extracellular domain of an EphB4protein, wherein the EphB4 polypeptide is a monomer and bindsspecifically to an Ephrin B2 polypeptide; (ii) a soluble polypeptidecomprising an amino acid sequence of an extracellular domain of anEphrin B2 protein, wherein the soluble Ephrin B2 polypeptide is amonomer and binds with high affinity to an EphB4 polypeptide; (iii) anantibody which binds to an extracellular domain of an EphB4 protein andinhibits an activity of the EphB4; and (iv) an antibody which binds toan extracellular domain of an Ephrin B2 protein and inhibits an activityof the Ephrin B2. Optionally, a method may comprise identifying in thepatient a tumor having a plurality of cancer cells having a geneamplification of the EphB4 and/or EphrinB2 gene.

In certain aspects, the disclosure provides methods for identifying atumor that is suitable for treatment with an EphrinB2 or EphB4antagonist. A method may comprise detecting in the tumor cell one ormore of the following characteristics: (a) expression of EphB4 proteinand/or mRNA; (b) expression of EphrinB2 protein and/or mRNA; (c) geneamplification of the EphB4 gene; or (d) gene amplification of theEphrinB2 gene. A tumor cell having one or more of characteristics(a)-(d) may be suitable for treatment with an EphrinB2 or EphB4antagonist, such as a polypeptide agent described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows amino acid sequence of the B4ECv3 protein (predictedsequence of the precursor including uncleaved Eph B4 leader peptide isshown).

FIG. 2 shows amino acid sequence of the B4ECv3NT protein (predictedsequence of the precursor including uncleaved Eph B4 leader peptide isshown).

FIG. 3 shows amino acid sequence of the B2EC protein (predicted sequenceof the precursor including uncleaved Ephrin B2 leader peptide is shown).

FIG. 4 shows amino acid sequence of the B4ECv3-FC protein (predictedsequence of the precursor including uncleaved Eph B4 leader peptide isshown).

FIG. 5 shows amino acid sequence of the B2EC-FC protein (predictedsequence of the precursor including uncleaved Ephrin B2 leader peptideis shown).

FIG. 6 shows B4EC-FC binding assay (Protein A-agarose based).

FIG. 7 shows B4EC-FC inhibition assay (Inhibition in solution).

FIG. 8 shows B2EC-FC binding assay (Protein-A-agarose based assay).

FIG. 9 shows chemotaxis of HUAEC in response to B4Ecv3.

FIG. 10 shows chemotaxis of HHEC in response to B2EC-FC.

FIG. 10 shows chemotaxis of HHAEC in response to B2EC.

FIG. 12 shows effect of B4Ecv3 on HUAEC tubule formation.

FIG. 13 shows effect of B2EC-FC on HUAEC tubule formation.

FIG. 14 is a schematic representation of human Ephrin B2 constructs.

FIG. 15 is a schematic representation of human EphB4 constructs.

FIG. 16 shows the domain structure of the recombinant soluble EphB4ECproteins. Designation of the domains are as follows: L—leader peptide,G—globular (ligand-binding domain), C—Cys-rich domain, F1,F2—fibronectin type III repeats, H—6×His-tag.

FIG. 17 shows purification and ligand binding properties of the EphB4ECproteins. A. SDS-PAAG gel electrophoresis of purified EphB4-derivedrecombinant soluble proteins (Coomassie-stained). B. Binding of EphrinB2-AP fusion to EphB4-derived recombinant proteins immobilized onNi—NTA-agarose beads. Results of three independent experiments are shownfor each protein. Vertical axis—optical density at 420 nm.

FIG. 18 shows that EphB4v3 inhibits chemotaxis.

FIG. 19 shows that EphB4v3 inhibits tubule formation on Matrigel. Adisplays the strong inhibition of tubule formation by B4v3 in arepresentative experiment. B shows a quantitation of the reduction oftube-length obtained with B4v3 at increasing concentrations as well as areduction in the number of junctions, in comparison to cells with noprotein. Results are displayed as mean values_S.D. obtained from threeindependent experiments performed with duplicate wells.

FIG. 20 shows that soluble EphB4 has no detectable cytotoxic effect asassessed by MTS assay.

FIG. 21 shows that B4v3 inhibits invasion and tubule formation byendothelial cells in the Matrigel assay. (A) to detect total invadingcells, photographed at 20× magnification or with Masson's Trichrome Topleft of A B displays section of a Matrigel plug with no GF, top right ofA displays section with B4IgG containing GF and lower left sectioncontains GF, and lower right shows GF in the presence of B4v3.Significant invasion of endothelial cells is only seeing GF containingMatrigel. Top right displays an area with a high number of invaded cellsinduced by B4IgG, which signifies the dimeric form of B4v3. The leftupper parts of the pictures correspond to the cell layers formed aroundthe Matrigel plug from which cells invade toward the center of the pluglocated in the direction of the right lower corner. Total cells insections of the Matrigel plugs were quantitated with Scion Imagesoftware. Results obtained from two experiments with duplicate plugs aredisplayed as mean values_S.D.

FIG. 22 shows tyrosine phosphorylation of EphB4 receptor in PC3 cells inresponse to stimulation with EphrinB2-Fc fusion in presence or absenceof EphB4-derived recombinant soluble proteins.

FIG. 23 shows effects of soluble EphB4ECD on viability and cell cycle.A) 3-day cell viability assay of two HNSCC cell lines. B) FACS analysisof cell cycle in HNSCC-15 cells treated as in A. Treatment of thesecells resulted in accumulation in subG0/G1 and S/G2 phases as indicatedby the arrows.

FIG. 24 shows that B4v3 inhibits neovascular response in a murinecorneal hydron micropocket assay.

FIG. 25 shows that that SCC15, B16, and MCF-7 co-injected with sB4v3 inthe presence of matrigel and growth factors, inhibits the in vivo tumorgrowth of these cells.

FIG. 26 shows that soluble EphB4 causes apoptosis, necrosis anddecreased angiogenesis in three tumor types, B16 melanoma, SCC15, headand neck carcinoma, and MCF-7 Breast carcinoma. Tumors were injectedpremixed with Matrigel plus growth factors and soluble EphB4subcutaneously. After 10 to 14 days, the mice were injectedintravenously with fitc-lectin (green) to assess blood vessel perfusion.Tumors treated with control PBS displayed abundant tumor density and arobust angiogenic response Tumors treated with sEphB4 displayed adecrease in tumor cell density and a marked inhibition of tumorangiogenesis in regions with viable tumor cells, as well as tumornecrosis and apoptosis.

FIG. 27 shows expression of EphB4 in prostate cell lines. A) Westernblot of total cell lysates of various prostate cancer cell lines, normalprostate gland derived cell line (MLC) and acute myeloblastic lymphomacells (AML) probed with EphB4 monoclonal antibody B) Phosphorylation ofEphB4 in PC-3 cells determined by Western blot.

FIG. 28 shows expression of EphB4 in prostate cancer tissue.Representative prostate cancer frozen section stained with EphB4monoclonal antibody (top left) or isotype specific control (bottomleft). Adjacent BPH tissue stained with EphB4 monoclonal antibody (topright). Positive signal is brown color in the tumor cells. Stroma andthe normal epithelia are negative. Note membrane localization of stainin the tumor tissue, consistent with trans-membrane localization ofEphB4. Representative QRT-PCR of RNA extracted from cancer specimens andadjacent BPH tissues (lower right).

FIG. 29 shows downregulation of EphB4 in prostate cancer cells by tumorsuppressors and RXR expression. A) PC3 cells were co-transfected withtruncated CD4 and p53 or PTEN or vector only. 24 h later CD4-sortedcells were collected, lysed and analyzed sequentially by Western blotfor the expression of EphB4 and β-actin, as a normalizer protein. B)Western blot as in (A) of various stable cell lines. LNCaP-FGF is astable transfection clone of FGF-8, while CWR22R-RXR stably expressesthe RXR receptor. BPH-1 was established from benign hypertrophicprostatic epithelium.

FIG. 30 shows downregulation of EphB4 in prostate cancer cells by EGFRand IGFR-1. A) Western blot of PC3 cells treated with or without EGFRspecific inhibitor AG1478 (1 nM) for 36 hours. Decreased EphB4 signal isobserved after AG 1478 treatment. The membrane was stripped and reprobedwith β-actin, which was unaffected. B) Western Blot of triplicatesamples of PC3 cells treated with or without IGFR-1 specificneutralizing antibody MAB391 (2 μg/ml;

overnight). The membrane was sequentially probed with EphB4, IGFR-1 andβ-actin antibodies. IGFR-1 signal shows the expected repression ofsignal with MAB391 treatment.

FIG. 31 shows effect of specific EphB4 AS-ODNs and siRNA on expressionand prostate cell functions. A) 293 cells stably expressing full-lengthconstruct of EphB4 was used to evaluate the ability of siRNA 472 toinhibit EphB4 expression. Cells were transfected with 50 nM RNAi usingLipofectamine 2000. Western blot of cell lysates 40 h post transfectionwith control siRNA (green fluorescence protein; GFP siRNA) or EphB4siRNA 472, probed with EphB4 monoclonal antibody, stripped and reprobedwith β-actin monoclonal antibody. B) Effect of EphB4 AS-10 on expressionin 293 transiently expressing full-length EphB4. Cells were exposed toAS-10 or sense ODN for 6 hours and analyzed by Western blot as in (A).C) 48 h viability assay of PC3 cells treated with siRNA as described inthe Methods section. Shown is mean±s.e.m. of triplicate samples. D)5-day viability assay of PC3 cells treated with ODNs as described in theMethods. Shown is mean±s.e.m. of triplicate samples. E) Scrape assay ofmigration of PC3 cells in the presence of 50 nM siRNAs transfected as in(A). Shown are photomicrographs of representative 20× fields takenimmediately after the scrape was made in the monolayer (0 h) and after20 h continued culture. A large number of cells have filled in thescrape after 20 h with control siRNA, but not with EphB4 siRNA 472. F)Shown is a similar assay for cells treated with AS-10 or sense ODN (both10 μM). G) Matrigel invasion assay of PC3 cells transfected with siRNAor control siRNA as described in the methods. Cells migrating to theunderside of the Matrigel coated insert in response to 5 mg/mlfibronectin in the lower chamber were fixed and stained with Giemsa.Shown are representative photomicrographs of control siRNA and siRNA 472treated cells. Cell numbers were counted in 5 individual high-poweredfields and the average±s.e.m. is shown in the graph (bottom right).

FIG. 32 shows effect of EphB4 siRNA 472 on cell cycle and apoptosis. A)PC3 cells transfected with siRNAs as indicated were analyzed 24 h posttransfection for cell cycle status by flow cytometry as described in theMethods. Shown are the plots of cell number vs. propidium iodidefluorescence intensity. 7.9% of the cell population is apoptotic (in theSub G0 peak) when treated with siRNA 472 compared to 1% with controlsiRNA. B) Apoptosis of PC3 cells detected by Cell Death DetectionELISA^(plus) kit as described in the Methods. Absorbance at 405 nmincreases in proportion to the amount of histone and DNA-POD in thenuclei-free cell fraction. Shown is the mean±s.e.m. of triplicatesamples at the indicated concentrations of siRNA 472 and GFP siRNA(control).

FIG. 33 shows that EphB4 and EphrinB2 are expressed in mesothelioma celllines as shown by RT-PCR (A) and Western Blot (B).

FIG. 34 shows expression of ephrin B2 and EphB4 by in situ hybridizationin mesothelioma cells. NCI H28 mesothelioma cell lines cultured inchamber slides hybridized with antisense probe to ephrin B2 or EphB4(top row). Control for each hybridization was sense (bottom row).Positive reaction is dark blue cytoplasmic stain.

FIG. 35 shows cellular expression of EphB4 and ephrin B2 in mesotheliomacultures. Immunofluorescence staining of primary cell isolate derivedfrom pleural effusion of a patient with malignant mesothelioma and celllines NCI H28, NCI H2373, and NCI H2052 for ephrin B2 and EphB4. Greencolor is positive signal for FITC labeled secondary antibody.Specificity of immunofluorescence staining was demonstrated by lack ofsignal with no primary antibody (first row). Cell nuclei werecounterstained with DAPI (blue color) to reveal location of all cells.Shown are merged images of DAPI and FITC fluorescence. Originalmagnification 200×.

FIG. 36 shows expression of ephrin B2 and EphB4 in mesothelioma tumor.Immunohistochemistry of malignant mesothelioma biopsy. H&E stainedsection to reveals tumor architecture; bottom left panel is backgroundcontrol with no primary antibody. EphB4 and ephrin B2 specific stainingis brown color. Original magnification 200×.

FIG. 37 shows effects of EPHB4 antisense probes (A) and EPHB4 siRNAs (B)on the growth of H28 cells.

FIG. 38 shows effects of EPHB4 antisense probes (A) and EPHB4 siRNAs (B)on cell migration.

FIG. 39 shows that EphB4 is expressed in HNSCC primary tissues andmetastases. A) Top: Immunohistochemistry of a representative archivalsection stained with EphB4 monoclonal antibody as described in themethods and visualized with DAB (brown color) localized to tumor cells.Bottom: Hematoxylin and Eosin (H&E) stain of an adjacent section. Densepurple staining indicates the presence of tumor cells. The right handcolumn are frozen sections of lymph node metastasis stained with EphB4polyclonal antibody (top right) and visualized with DAB. Control(middle) was incubation with goat serum and H&E (bottom) reveals thelocation of the metastatic foci surrounded by stroma which does notstain. B) In situ hybridization of serial frozen sections of a HNSCCcase probed with EphB4 (left column) and ephrin B2 (right column) DIGlabeled antisense or sense probes generated by run-off transcription.Hybridization signal (dark blue) was detected usingalkaline-phosphatase-conjugated anti-DIG antibodies and sections werecounterstained with Nuclear Fast Red. A serial section stained with H&Eis shown (bottom left) to illustrate tumor architecture. C) Western blotof protein extract of patient samples consisting of tumor (T),uninvolved normal tissue (N) and lymph node biopsies (LN). Samples werefractionated by polyacrylamide gel electrophoresis in 4-20% Tris-glycinegels and subsequently electroblotted onto nylon membranes. Membraneswere sequentially probed with EphB4 monoclonal antibody and β-actinMoAb. Chemiluminescent signal was detected on autoradiography film.Shown is the EphB4 specific band which migrated at 120 kD and β-actinwhich migrated at 40 kD. The β-actin signal was used to control forloading and transfer of each sample.

FIG. 40 shows that EphB4 is expressed in HNSCC cell lines and isregulated by EGF: A) Survey of EphB4 expression in SCC cell lines.Western blot of total cell lysates sequentially probed with EphB4monoclonal antibody, stripped and reprobed with β-actin monoclonalantibody as described for FIG. 39C. B) Effect of the specific EGFRinhibitor AG1478 on EphB4 expression: Western blot of crude cell lysatesof SCC15 treated with 0-1000 nM AG 1478 for 24 h in media supplementedwith 10% FCS (left) or with 1 mM AG 1478 for 4, 8, 12 or 24 h (right).Shown are membranes sequentially probed for EphB4 and β-actin. C) Effectof inhibition of EGFR signaling on EphB4 expression in SCC cell lines:Cells maintained in growth media containing 10% FCS were treated for 24hr with 1 μM AG 1478, after which crude cell lysates were analyzed byWestern blots of cell lysates sequentially probed with for EGFR, EphB4,ephrin B2 and β-actin antibodies. Specific signal for EGFR was detectedat 170 kD and ephrin B2 at 37 kD in addition to EphB4 and β-actin asdescribed in FIG. 1C. β-actin serves as loading and transfer control.

FIG. 41 shows mechanism of regulation of EphB4 by EGF: A) Schematic ofthe EGFR signaling pathways, showing in red the sites of action andnames of specific kinase inhibitors used. B) SCC 15 cells wereserum-starved for 24 h prior to an additional 24 incubation as indicatedwith or without EGF (10 ng/ml), 3 μM U73122, or 5 μM SH-5, 5 μMSP600125, 25 nM LY294002,—μM PD098095 or 5 μM SB203580. N/A indicatescultures that received equal volume of diluent (DMSO) only. Cell lysateswere subjected to Western Blot with EphB4 monoclonal antibody. β-actinsignal serves as control of protein loading and transfer.

FIG. 42 shows that specific EphB4 siRNAs inhibit EphB4 expression, cellviability and cause cell cycle arrest. A) 293 cells stably expressingfull length EphB4 were transfected with 50 nM RNAi using Lipofectarnine™2000. 40 h post-transfection cells were harvested, lysed and processedfor Western blot. Membranes were probed with EphB4 monoclonal antibody,stripped and reprobed with β-actin monoclonal antibody as control forprotein loading and transfer. Negative reagent control was RNAi toscrambled green fluorescence protein (GFP) sequence and control istransfection with Lipofectamine™ 2000 alone. B) MTT cell viabilityassays of SCC cell lines treated with siRNAs for 48 h as described inthe Methods section. Shown is mean+s.e.m. of triplicate samples. C)SCC15 cells transfected with siRNAs as indicated were analyzed 24 h posttransfection for cell cycle status by flow cytometry as described in theMethods. Shown are the plots of cell number vs. propidium iodidefluorescence intensity. Top and middle row show plots for cells 16 hafter siRNA transfection, bottom row shows plots for cells 36 h posttransfection. Specific siRNA and concentration are indicated for eachplot. Lipo=Lipofectamine™200 mock transfection.

FIG. 43 shows in vitro effects of specific EphB4 AS-ODNs on SCC cells.A) 293 cells transiently transfected with EphB4 full-length expressionplasmid were treated 6 h post transfection with antisense ODNs asindicated. Cell lysates were collected 24 h after AS-ODN treatment andsubjected to Western Blot. B) SCC25 cells were seeded on 48 well platesat equal densities and treated with EphB4 AS-ODNs at 1, 5, and 10 μM ondays 2 and 4. Cell viability was measured by MTT assay on day 5. Shownis the means+s.e.m. of triplicate samples. Note that AS-ODNs that wereactive in inhibiting EphB4 protein levels were also effective inhibitorsof SCC15 cell viability. C) Cell cycle analysis of SCC15 cells treatedfor 36 h with AS-10 (bottom) compared to cells that were not treated(top). D) Confluent cultures of SCC 15 cells scraped with a plasticPasteur pipette to produce 3 mm wide breaks in the monolayer. Theability of the cells to migrate and close the wound in the presence ofinhibiting EphB4 AS-ODN (AS-10) and non-inhibiting AS-ODN (AS-1) wasassessed after 48 h. Scrambled ODN is included as a negative controlODN. Culture labeled no treatment was not exposed to ODN. At initiationof the experiment, all cultures showed scrapes of equal width andsimilar to that seen in 1 μM EphB4 AS-10 after 48 h. The red bracketsindicate the width of the original scrape. E) Migration of SCC15 cellsin response to 20 mg/ml EGF in two-chamber assay as described in theMethods. Shown are representative photomicrographs of non-treated (NT),AS-6 and AS-10 treated cells and 10 ng/ml Taxol as positive control ofmigration inhibition. F) Cell numbers were counted in 5 individualhigh-powered fields and the average+s.e.m. is shown in the graph.

FIG. 44 shows that EphB4 AS-ODN inhibits tumor growth in vivo. Growthcurves for SCC15 subcutaneous tumor xenografts in Balb/C nude micetreated with EphB4 AS-10 or scrambled ODN at 20 mg/kg/day starting theday following implantation of 5×106 cells. Control mice received andequal volume of diluent (PBS). Shown are the mean+s.e.m. of 6mice/group. *P=0.0001 by Student's t-test compared to scrambled ODNtreated group.

FIG. 45 shows that Ephrin B2, but not EpbB4 is expressed in KS biopsytissue. (A) In situ hybridization with antisense probes for ephrin B2and EphB4 with corresponding H&E stained section to show tumorarchitecture. Dark blue color in the ISH indicates positive reaction forephrin B2. No signal for EphB4 was detected in the Kaposi's sarcomabiopsy. For contrast, ISH signal for EphB4 is strong in squamous cellcarcinoma tumor cells. Ephrin B2 was also detected in KS using EphB4-APfusion protein (bottom left). (B) Detection of ephrin B2 with EphB4/Fcfusion protein. Adjacent sections were stained with H&E (left) to showtumor architecture, black rectangle indicates the area shown in theEphB4/Fc treated section (middle) detected with FITC-labeled anti-humanFc antibody as described in the methods section. As a control anadjacent section was treated with human Fc fragment (right). Specificsignal arising from EphB4/Fc binding to the section is seen only inareas of tumor cells. (C) Co-expression of ephrin B2 and the HHV8latency protein LANA1. Double-label confocal immunofluorescencemicroscopy with antibodies to ephrin B2 (red) LANA1 (green), or EphB4(red) of frozen KS biopsy material directly demonstrates co-expressionof LANA1 and ephrin B2 in KS biopsy. Coexpression is seen as yellowcolor. Double label confocal image of biopsy with antibodies to PECAM-1(green) in cells with nuclear propidium iodide stain (red),demonstrating the vascular nature of the tumor.

FIG. 46 shows that HHV-8 induces arterial marker expression in venousendothelial cells. (A) Immunofluorescence of cultures of HUVEC andHUVEC/BC-1 for artery/vein markers and viral proteins. Cultures weregrown on chamber slides and processed for immunofluorescence detectionof ephrin B2 (a, e, i), EphB4 (m, q, u), CD148 (j, v), and the HHV-8proteins LANA1 (b, f, m) or ORF59 (r) as described in the Materials andMethods. Yellow color in the merged images of the same field demonstrateco-expression of ephrin B2 and LANA or ephrin B2 and CD148. Thepositions of viable cells were revealed by nuclear staining with DAPI(blue) in the third column (c, g, k, o, s, w). Photomicrographs are ofrepresentative fields. (B) RT-PCR of HUVEC and two HHV-8 infectedcultures (HUVEC/BC-1 and HUVEC/BC-3) for ephrin B2 and EphB4. Ephrin B2product (200 bp) is seen in HUVEC/BC-1, HUVEC/BC-3 and EphB4 product(400 bp) is seen in HUVEC. Shown also is β-actin RT-PCR as a control foramount and integrity of input RNA.

FIG. 47 shows that HHV-8 induces arterial marker expression in Kaposi'ssarcoma cells. (A) Western blot for ephrin B2 on various cell lysates.SLK-vGPCR is a stable clone of SLK expressing the HHV-8 vGPCR, andSLK-pCEFL is control stable clone transfected with empty expressionvector. SLK cells transfected with LANA or LANAΔ440 are SLK-LANA andSLK-Δ440 respectively. Quantity of protein loading and transfer wasdetermined by reprobing the membranes with β-actin monoclonal antibody.(B) Transient transfection of KS-SLK cells with expression vectorpvGPCR-CEFL resulted in the expression of ephrin B2 as shown byimmunofluorescence staining with FITC (green), whereas the controlvector pCEFL had no effect. KS-SLK cells (0.8×105/well) were transfectedwith 0.8 μg DNA using Lipofectamine 2000. 24 hr later cells were fixedand stained with ephrin B2 polyclonal antibody and FITC conjugatedsecondary antibody as described in the methods. (C) Transienttransfection of HWVEC with vGPCR induces transcription from ephrin B2luciferase constructs. 8×103 Ht1VEC in 24 well plates were transfectedusing Superfect with 0.8 μg/well ephrin B2 promoter constructscontaining sequences from −2941 to −11 with respect to the translationstart site, or two 5′-deletions as indicated, together with 80 ng/wellpCEFL or pvGPCR-CEFL. Luciferase was determined 48 h post transfectionand induction ratios are shown to the right of the graph. pGL3Basic ispromoterless luciferase control vector. Luciferase was normalized toprotein since GPCR induced expression of the cotransfectedβ-galactosidase. Graphed is mean+SEM of 6 replicates. Shown is one ofthree similar experiments.

FIG. 48 shows that VEGF and VEGF-C regulate ephrin B2 expression. A)Inhibition of ephrin B2 by neutralizing antibodies. Cells were culturedin full growth medium and exposed to antibody (100 ng/ml) for 36 hrbefore collection and lysis for Western blot. B) For induction of ephrinB2 expression cells were cultured in EBM growth medium containing 5%serum lacking growth factors. Individual growth factors were added asindicated and the cells harvested after 36 h. Quantity of proteinloading and transfer was determined by reprobing the membranes β-actinmonoclonal antibody.

FIG. 49 shows that Ephrin B2 knock-down with specific siRNA inhibitsviability in KS cells and HUVEC grown in the presence of VEGF but notIGF, EGF or bFGF. A) KS-SLK cells were transfected with various siRNA toephrin B2 and controls. After 48 hr the cells were harvested and crudecell lysates fractionated on 4-20% SDS-PAGE. Western blot was performedwith monoclonal antibody to ephrin B2 generated in-house. The membranewas stripped and reprobed with β-actin monoclonal antibody (Sigma) toillustrate equivalent loading and transfer. B) 3 day cell viabilityassay of KS-SLK cultures in the presence of ephrin B2 and EphB4 siRNAs.1×10⁵ cells/well in 24-well plates were treated with 0, 10 and 100 ng/mlsiRNAs as indicated on the graph. Viability of cultures was determinedby MTT assay as described in the methods section. Shown are themeans+standard deviation of duplicate samples. C) HUVE cells were seededon eight wells chamber slides coated with fibronectin. The HUVE cellswere grown overnight in EGM-2 media, which contains all growthsupplements. On the following day, the media was replaced with mediacontaining VEGF (10 ng/ml) or EGF, FGF and IGF as indicated. After 2 hrsof incubation at 37° C., the cells were transfected using Lipofectamine2000 (Invitrogen) in Opti-MEM medium containing 10 nM of siRNA to ephrinB2, Eph B4 or green fluorescence protein (GFP) as control. The cellswere incubated for 2 hr and then the fresh media containing growthfactors or VEGF alone was added to their respective wells. After 48 hrs,the cells were stained with crystal violet and the pictures were takenimmediately by digital camera at 10× magnification.

FIG. 50 shows that soluble EphB4 inhibits KS and EC cord formation andin vivo angiogenesis. Cord formation assay of HUVEC in Matrigel™ (upperrow). Cells in exponential growth phase were treated overnight with theindicated concentrations of EphB4 extracellular domain (ECD) prior toplating on Matrigel™. Cells were trypsinized and plated (1×10⁵cells/well) in a 24-well plate containing 0.5 ml Matrigel™. Shown arerepresentative 20× phase contrast fields of cord formation after 8 hrplating on Matrigel™ in the continued presence of the test compounds asshown. Original magnification 200×. KS-SLK cells treated in a similarmanner (middle row) in a cord formation assay on Matrigel™. Bottom rowshows in vivo Matrigel™ assay: Matrigel™ plugs containing growth factorsand EphB4 ECD or PBS were implanted subcutaneously in the mid-ventralregion of mice. After 7 days the plugs were removed, sectioned andstained with H&E to visualize cells migrating into the matrix. Intactvessels with large lumens are observed in the control, whereas EphB4 ECDalmost completely inhibited migration of cells into the Matrigel.

FIG. 51 shows expression of EPHB4 in bladder cancer cell lines (A), andregulation of EPHB4 expression by EGFR signaling pathway (B).

FIG. 52 shows that transfection of p53 inhibit the expression of EPBB4in 5637 cell.

FIG. 53 shows growth inhibition of bladder cancer cell line (5637) upontreatment with EPHB4 siRNA 472.

FIG. 54 shows results on apoptosis study of 5637 cells transfected withEPHB4 siRNA 472.

FIG. 55 shows effects of EPHB4 antisense probes on cell migration. 5637cells were treated with EPHB4AS10 (10 μM).

FIG. 56 shows effects of EPHB4 siRNA on cell invasion. 5637 cells weretransfected with siRNA 472 or control siRNA.

FIG. 57 shows comparison of EphB4 monoclonal antibodies by G250 and inpull-down assay.

FIG. 58 shows that EphB4 antibodies inhibit the growth of SCC15xenograft tumors.

FIG. 59 shows that EphB4 antibodies cause apoptosis, necrosis anddecreased angiogenesis in SCC15, head and neck carcinoma tumor type.

FIG. 60 shows that systemic administration of EphB4 antibodies leads totumor regression.

FIG. 61 shows a genomic nucleotide sequence of human EphB4.

FIG. 62 shows a cDNA nucleotide sequence of human EphB4.

FIG. 63 shows a genomic nucleotide sequence of human Ephrin B2.

FIG. 64 shows a cDNA nucleotide sequence of human Ephrin B2.

FIG. 65 shows an amino acid sequence of human EphB4.

FIG. 66 shows an amino acid sequence of human Ephrin B2.

DETAILED DESCRIPTION OF THE INVENTION

I. Overview

The current invention is based in part on the discovery that signalingthrough the ephrin/ephrin receptor pathway contributes to tumorigenesis.Applicants detected expression of ephrin B2 and EphB4 in tumor tissuesand developed anti-tumor therapeutic agents for blocking signalingthrough the ephrin/ephrin receptor. In addition, the disclosure providespolypeptide therapeutic agents and methods for polypeptide-basedinhibition of the function of EphB4 and/or Ephrin B2. Accordingly, incertain aspects, the disclosure provides numerous polypeptide compounds(agents) that may be used to treat cancer as well as angiogenesisrelated disorders and unwanted angiogenesis related processes.

As used herein, the terms Ephrin and Eph are used to refer,respectively, to ligands and receptors. They can be from any of avariety of animals (e.g., mammals/non-mammals,vertebrates/non-vertebrates, including humans). The nomenclature in thisarea has changed rapidly and the terminology used herein is thatproposed as a result of work by the Eph Nomenclature Committee, whichcan be accessed, along with previously-used names at web sitehttp://www.eph-nomenclature.com.

The work described herein, particularly in the examples, refers toEphrin B2 and EphB4. However, the present invention contemplates anyephrin ligand and/or Eph receptor within their respective family, whichis expressed in a tumor. The ephrins (ligands) are of two structuraltypes, which can be further subdivided on the basis of sequencerelationships and, functionally, on the basis of the preferentialbinding they exhibit for two corresponding receptor subgroups.Structurally, there are two types of ephrins: those which aremembrane-anchored by a glycerophosphatidylinositol (GPI) linkage andthose anchored through a transmembrane domain. Conventionally, theligands are divided into the Ephrin-A subclass, which are GPI-linkedproteins which bind preferentially to EphA receptors, and the Ephrin-Bsubclass, which are transmembrane proteins which generally bindpreferentially to EphB receptors.

The Eph family receptors are a family of receptor protein-tyrosinekinases which are related to Eph, a receptor named for its expression inan erythropoietin-producing human hepatocellular carcinoma cell line.They are divided into two subgroups on the basis of the relatedness oftheir extracellular domain sequences and their ability to bindpreferentially to Ephrin-A proteins or Ephrin-B proteins. Receptorswhich interact preferentially with Ephrin-A proteins are EphA receptorsand those which interact preferentially with Ephrin-B proteins are EphBreceptors.

Eph receptors have an extracellular domain composed of theligand-binding globular domain, a cysteine rich region followed by apair of fibronectin type III repeats (e.g., see FIG. 16). Thecytoplasmic domain consists of ajuxtamembrane region containing twoconserved tyrosine residues; a protein tyrosine kinase domain; a sterilea-motif (SAM) and a PDZ-domain binding motif. EphB4 is specific for themembrane-bound ligand Ephrin B2 (Sakano, S. et al 1996; Brambilla R. etal 1995). Ephrin B2 belongs to the class of Eph ligands that have atransmembrane domain and cytoplasmic region with five conserved tyrosineresidues and PDZ domain. Eph receptors are activated by binding ofclustered, membrane attached ephrins (Davis S et al, 1994), indicatingthat contact between cells expressing the receptors and cells expressingthe ligands is required for Eph activation.

Upon ligand binding, an Eph receptor dimerizes and autophosphorylate thejuxtamembrane tyrosine residues to acquire full activation (Kalo MS etal, 1999, Binns K S, 2000). In addition to forward signaling through theEph receptor, reverse signaling can occur through the ephrin Bs. Ephengagement of ephrins results in rapid phosphorylation of the conservedintracellular tyrosines (Bruckner K, 1997) and somewhat slowerrecruitment of PDZ binding proteins (Palmer A 2002). Recently, severalstudies have shown that high expression of Eph/ephrins may be associatedwith increased potentials for tumor growth, tumorigenicity, andmetastasis (Easty D J, 1999; Kiyokawa E, 1994; Tang X X, 1999; Vogt T,1998; Liu W, 2002; Stephenson S A, 2001; Steube K G 1999; Berclaz G,1996).

In certain embodiments, the present invention provides polypeptidetherapeutic agents that inhibit activity of Ephrin B2, EphB4, or both.As used herein, the term “polypeptide therapeutic agent” or “polypeptideagent” is a generic term which includes any polypeptide that blockssignaling through the Ephrin B2/EphB4 pathway. A preferred polypeptidetherapeutic agent of the invention is a soluble polypeptide of Ephrin B2or EphB4. Another preferred polypeptide therapeutic agent of theinvention is an antagonist antibody that binds to Ephrin B2 or EphB4.For example, such polypeptide therapeutic agent can inhibit function ofEphrin B2 or EphB4, inhibit the interaction between Ephrin B2 and EphB4,inhibit the phosphorylation of Ephrin B2 or EphB4, or inhibit any of thedownstream signaling events upon binding of Ephrin B2 to EphB4.

II. Soluble Polypeptides

In certain aspects, the invention relates to a soluble polypeptidecomprising an extracellular domain of an Ephrin B2 protein (referred toherein as an Ephrin B2 soluble polypeptide) or comprising anextracellular domain of an EphB4 protein (referred to herein as an EphB4soluble polypeptide). Preferably, the subject soluble polypeptide is amonomer and is capable of binding with high affinity to Ephrin B2 orEphB4. In a specific embodiment, the EphB4 soluble polypeptide of theinvention comprises a globular domain of an EphB4 protein. Specificexamples EpbB4 soluble polypeptides are provided in FIGS. 1, 2, and 15.Specific examples of Ephrin B2 soluble polypeptides are provided inFIGS. 3 and 14.

As used herein, the subject soluble polypeptides include fragments,functional variants, and modified forms of EphB4 soluble polypeptide oran Ephrin B2 soluble polypeptide. These fragments, functional variants,and modified forms of the subject soluble polypeptides antagonizefunction of EphB4, Ephrin B2 or both.

In certain embodiments, isolated fragments of the subject solublepolypeptides can be obtained by screening polypeptides recombinantlyproduced from the corresponding fragment of the nucleic acid encoding anEphB4 or Ephrin B2 soluble polypeptides. In addition, fragments can bechemically synthesized using techniques known in the art such asconventional Merrifield solid phase f-Moc or t-Boc chemistry. Thefragments can be produced (recombinantly or by chemical synthesis) andtested to identify those peptidyl fragments that can function to inhibitfunction of EphB4 or Ephrin B2, for example, by testing the ability ofthe fragments to inhibit angiogenesis or tumor growth.

In certain embodiments, a functional variant of an EphB4 solublepolypeptide has an amino acid sequence that is at least 90%, 95%, 97%,99% or 100% identical to residues 1-522, residues 1-412, or residues1-312 of the amino acid sequence defined by FIG. 65. In otherembodiments, a functional variant of an Ephrin B2 soluble polypeptidehas a sequence at least 90%, 95%, 97%, 99% or 100% identical to residues1-225 of the amino acid sequence defined by FIG. 66.

In certain embodiments, the present invention contemplates makingfunctional variants by modifying the structure of the subject solublepolypeptide for such purposes as enhancing therapeutic or prophylacticefficacy, or stability (e.g., ex vivo shelf life and resistance toproteolytic degradation in vivo). Such modified soluble polypeptide areconsidered functional equivalents of the naturally-occurring EphB4 orEphrin B2 soluble polypeptide. Modified soluble polypeptides can beproduced, for instance, by amino acid substitution, deletion, oraddition. For instance, it is reasonable to expect, for example, that anisolated replacement of a leucine with an isoleucine or valine, anaspartate with a glutamate, a threonine with a serine, or a similarreplacement of an amino acid with a structurally related amino acid(e.g., conservative mutations) will not have a major effect on thebiological activity of the resulting molecule. Conservative replacementsare those that take place within a family of amino acids that arerelated in their side chains.

This invention further contemplates a method of generating sets ofcombinatorial mutants of the EphB4 or Ephrin B2 soluble polypeptides, aswell as truncation mutants, and is especially useful for identifyingfunctional variant sequences. The purpose of screening suchcombinatorial libraries may be to generate, for example, solublepolypeptide variants which can act as antagonists of EphB4, EphB2, orboth. Combinatorially-derived variants can be generated which have aselective potency relative to a naturally occurring soluble polypeptide.Such variant proteins, when expressed from recombinant DNA constructs,can be used in gene therapy protocols. Likewise, mutagenesis can giverise to variants which have intracellular half-lives dramaticallydifferent than the corresponding wild-type soluble polypeptide. Forexample, the altered protein can be rendered either more stable or lessstable to proteolytic degradation or other cellular process which resultin destruction of, or otherwise inactivation of the protein of interest(e.g., a soluble polypeptide). Such variants, and the genes which encodethem, can be utilized to alter the subject soluble polypeptide levels bymodulating their half-life. For instance, a short half-life can giverise to more transient biological effects and, when part of an inducibleexpression system, can allow tighter control of recombinant solublepolypeptide levels within the cell. As above, such proteins, andparticularly their recombinant nucleic acid constructs, can be used ingene therapy protocols.

There are many ways by which the library of potential homologs can begenerated from a degenerate oligonucleotide sequence. Chemical synthesisof a degenerate gene sequence can be carried out in an automatic DNAsynthesizer, and the synthetic genes then be ligated into an appropriategene for expression. The purpose of a degenerate set of genes is toprovide, in one mixture, all of the sequences encoding the desired setof potential soluble polypeptide sequences. The synthesis of degenerateoligonucleotides is well known in the art (see for example, Narang, S A(1983) Tetrahedron 39:3; Itakura et al., (1981) Recombinant DNA, Proc.3rd Cleveland Sympos. Macromolecules, ed. A G Walton, Amsterdam:Elsevier pp273-289; Itakura et al., (1984) Annu. Rev. Biochem. 53:323;Itakura et al., (1984) Science 198:1056; Ike et al., (1983) Nucleic AcidRes. 11:477). Such techniques have been employed in the directedevolution of other proteins (see, for example, Scott et al., (1990)Science 249:386-390; Roberts et al., (1992) PNAS USA 89:2429-2433;Devlin et al., (1990) Science 249: 404-406; Cwirla et al., (1990) PNASUSA 87:6378-6382; as well as U.S. Pat. Nos: 5,223,409, 5,198,346, and5,096,815).

Alternatively, other forms of mutagenesis can be utilized to generate acombinatorial library. For example, soluble polypeptide variants (e.g.,the antagonist forms) can be generated and isolated from a library byscreening using, for example, alanine scanning mutagenesis and the like(Ruf et al., (1994) Biochemistry 33:1565-1572; Wang et al., (1994) J.Biol. Chem. 269:3095-3099; Balint et al., (1993) Gene 137:109-118;Grodberg et al., (1993) Eur. J. Biochem. 218:597-601; Nagashima et al.,(1993) J. Biol. Chem. 268:2888-2892; Lowman et al., (1991) Biochemistry30:10832-10838; and Cunningham et al., (1989) Science 244:1081-1085), bylinker scanning mutagenesis (Gustin et al., (1993) Virology 193:653-660;Brown et al., (1992) Mol. Cell Biol. 12:2644-2652; McKnight et al.,(1982) Science 232:316); by saturation mutagenesis (Meyers et al.,(1986) Science 232:613); by PCR mutagenesis (Leung et al., (1989) MethodCell Mol Biol 1:11-19); or by random mutagenesis, including chemicalmutagenesis, etc. (Miller et al., (1992) A Short Course in BacterialGenetics, CSHL Press, Cold Spring Harbor, N.Y.; and Greener et al.,(1994) Strategies in Mol Biol 7:32-34). Linker scanning mutagenesis,particularly in a combinatorial setting, is an attractive method foridentifying truncated (bioactive) forms of the subject solublepolypeptide.

A wide range of techniques are known in the art for screening geneproducts of combinatorial libraries made by point mutations andtruncations, and, for that matter, for screening cDNA libraries for geneproducts having a certain property. Such techniques will be generallyadaptable for rapid screening of the gene libraries generated by thecombinatorial mutagenesis of the subject soluble polypeptides. The mostwidely used techniques for screening large gene libraries typicallycomprises cloning the gene library into replicable expression vectors,transforming appropriate cells with the resulting library of vectors,and expressing the combinatorial genes under conditions in whichdetection of a desired activity facilitates relatively easy isolation ofthe vector encoding the gene whose product was detected. Each of theillustrative assays described below are amenable to high through-putanalysis as necessary to screen large numbers of degenerate sequencescreated by combinatorial mutagenesis techniques.

In certain embodiments, the subject soluble polypeptides of theinvention include a a small molecule such as a peptide and apeptidomimetic. As used herein, the term “peptidomimetic” includeschemically modified peptides and peptide-like molecules that containnon-naturally occurring amino acids, peptoids, and the like.Peptidomimetics provide various advantages over a peptide, includingenhanced stability when administered to a subject. Methods foridentifying a peptidomimetic are well known in the art and include thescreening of databases that contain libraries of potentialpeptidomimetics. For example, the Cambridge Structural Database containsa collection of greater than 300,000 compounds that have known crystalstructures (Allen et al., Acta Crystallogr. Section B, 35:2331 (1979)).Where no crystal structure of a target molecule is available, astructure can be generated using, for example, the program CONCORD(Rusinko et al., J. Chem. Inf. Comput. Sci. 29:251 (1989)). Anotherdatabase, the Available Chemicals Directory (Molecular Design Limited,Informations Systems; San Leandro Calif.), contains about 100,000compounds that are commercially available and also can be searched toidentify potential peptidomimetics of the EphB4 or Ephrin B2 solublepolypeptides.

To illustrate, by employing scanning mutagenesis to map the amino acidresidues of a soluble polypeptide which are involved in binding toanother protein, peptidomimetic compounds can be generated which mimicthose residues involved in binding. For instance, non-hydrolyzablepeptide analogs of such residues can be generated using benzodiazepine(e.g., see Freidinger et al., in Peptides: Chemistry and Biology, G. R.Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988), azepine(e.g., see Huffman et al., in Peptides: Chemistry and Biology, G. R.Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988), substitutedgamma lactam rings (Garvey et al., in Peptides: Chemistry and Biology,G. R. Marshall ed., ESCOM Publisher: Leiden, Netherlands, 1988),keto-methylene pseudo peptides (Ewenson et al., (1986) J. Med. Chem.29:295; and Ewenson et al., in Peptides: Structure and Function(Proceedings of the 9th American Peptide Symposium) Pierce Chemical Co.Rockland, Ill., 1985), b-turn dipeptide cores (Nagai et al., (1985)Tetrahedron Lett 26:647; and Sato et al., (1986) J Chem Soc Perkin Trans1:1231), and b-aminoalcohols (Gordon et al., (1985) Biochem Biophys ResCommun 126:419; and Dann et al., (1986) Biochem Biophys Res Commun134:71).

In certain embodiments, the soluble polypeptides of the invention mayfurther comprise post-translational modifications. Such modificationsinclude, but are not limited to, acetylation, carboxylation,glycosylation, phosphorylation, lipidation, and acylation. As a result,the modified soluble polypeptides may contain non-amino acid elements,such as polyethylene glycols, lipids, poly- or mono-saccharide, andphosphates. Effects of such non-amino acid elements on the functionalityof a soluble polypeptide may be tested for its antagozing role in EphB4or Ephrin B2 function, e.g, it inhibitory effect on angiogenesis or ontumor growth.

In certain aspects, functional variants or modified forms of the subjectsoluble polypeptides include fusion proteins having at least a portionof the soluble polypeptide and one or more fusion domains. Well knownexamples of such fusion domains include, but are not limited to,polyhistidine, Glu-Glu, glutathione S transferase (GST), thioredoxin,protein A, protein G, and an immunoglobulin heavy chain constant region(Fc), maltose binding protein (MBP), which are particularly useful forisolation of the fusion proteins by affinity chromatography. For thepurpose of affinity purification, relevant matrices for affinitychromatography, such as glutathione-, amylase-, and nickel- orcobalt-conjugated resins are used. Another fusion domain well known inthe art is green fluorescent protein (GFP). Fusion domains also include“epitope tags,” which are usually short peptide sequences for which aspecific antibody is available. Well known epitope tags for whichspecific monoclonal antibodies are readily available include FLAG,influenza virus haemagglutinin (HA), and c-myc tags. In some cases, thefusion domains have a protease cleavage site, such as for Factor Xa orThrombin, which allows the relevant protease to partially digest thefusion proteins and thereby liberate the recombinant proteins therefrom.The liberated proteins can then be isolated from the fusion domain bysubsequent chromatographic separation. In certain embodiments, thesoluble polypeptides of the present invention contain one or moremodifications that are capable of stabilizing the soluble polypeptides.For example, such modifications enhance the in vitro half life of thesoluble polypeptides, enhance circulatory half life of the solublepolypeptides or reducing proteolytic degradation of the solublepolypeptides.

In certain embodiments, soluble polypeptides (unmodified or modified) ofthe invention can be produced by a variety of art-known techniques. Forexample, such soluble polypeptides can be synthesized using standardprotein chemistry techniques such as those described in Bodansky, M.Principles of Peptide Synthesis, Springer Verlag, Berlin (1993) andGrant G. A. (ed.), Synthetic Peptides: A User's Guide, W. H. Freeman andCompany, New York (1992). In addition, automated peptide synthesizersare commercially available (e.g., Advanced ChemTech Model 396;Milligen/Biosearch 9600). Alternatively, the soluble polypeptides,fragments or variants thereof may be recombinantly produced usingvarious expression systems as is well known in the art (also see below).

III. Nucleic Acids Encoding Soluble Polypeptides

In certain aspects, the invention relates to isolated and/or recombinantnucleic acids encoding an EphB4 or Ephrin B2 soluble polypeptide. Thesubject nucleic acids may be single-stranded or double-stranded, DNA orRNA molecules. These nucleic acids are useful as therapeutic agents. Forexample, these nucleic acids are useful in making recombinant solublepolypeptides which are administered to a cell or an individual astherapeutics. Alternative, these nucleic acids can be directlyadministered to a cell or an individual as therapeutics such as in genetherapy.

In certain embodiments, the invention provides isolated or recombinantnucleic acid sequences that are at least 80%, 85%, 90%, 95%, 97%, 98%,99% or 100% identical to a region of the nucleotide sequence depicted inFIG. 62 or 63. One of ordinary skill in the art will appreciate thatnucleic acid sequences complementary to the subject nucleic acids, andvariants of the subject nucleic acids are also within the scope of thisinvention. In further embodiments, the nucleic acid sequences of theinvention can be isolated, recombinant, and/or fused with a heterologousnucleotide sequence, or in a DNA library.

In other embodiments, nucleic acids of the invention also includenucleotide sequences that hybridize under highly stringent conditions tothe nucleotide sequence depicted in FIG. 62 or 63, or complementsequences thereof. As discussed above, one of ordinary skill in the artwill understand readily that appropriate stringency conditions whichpromote DNA hybridization can be varied. One of ordinary skill in theart will understand readily that appropriate stringency conditions whichpromote DNA hybridization can be varied. For example, one could perform

the hybridization at 6.0× sodium chloride/sodium citrate (SSC) at about45° C., followed by a wash of 2.0×SSC at 50° C. For example, the saltconcentration in the wash step can be selected from a low stringency ofabout 2.0×SSC at 50° C. to a high stringency of about 0.2×SSC at 50° C.In addition, the temperature in the wash step can be increased from lowstringency conditions at room temperature, about 22° C., to highstringency conditions at about 65° C. Both temperature and salt may bevaried, or temperature or salt concentration may be held constant whilethe other variable is changed. In one embodiment, the invention providesnucleic acids which hybridize under low stringency conditions of 6×SSCat room temperature followed by a wash at 2×SSC at room temperature.

Isolated nucleic acids which differ from the subject nucleic acids dueto degeneracy in the genetic code are also within the scope of theinvention. For example, a number of amino acids are designated by morethan one triplet. Codons that specify the same amino acid, or synonyms(for example, CAU and CAC are synonyms for histidine) may result in“silent” mutations which do not affect the amino acid sequence of theprotein. However, it is expected that DNA sequence polymorphisms that dolead to changes in the amino acid sequences of the subject proteins willexist among mammalian cells. One skilled in the art will appreciate thatthese variations in one or more nucleotides (up to about 3-5% of thenucleotides) of the nucleic acids encoding a particular protein mayexist among individuals of a given species due to natural allelicvariation. Any and all such nucleotide variations and resulting aminoacid polymorphisms are within the scope of this invention.

In certain embodiments, the recombinant nucleic acids of the inventionmay be operably linked to one or more regulatory nucleotide sequences inan expression construct. Regulatory nucleotide sequences will generallybe appropriate for a host cell used for expression. Numerous types ofappropriate expression vectors and suitable regulatory sequences areknown in the art for a variety of host cells. Typically, said one ormore regulatory nucleotide sequences may include, but are not limitedto, promoter sequences, leader or signal sequences, ribosomal bindingsites, transcriptional start and termination sequences, translationalstart and termination sequences, and enhancer or activator sequences.Constitutive or inducible promoters as known in the art are contemplatedby the invention. The promoters may be either naturally occurringpromoters, or hybrid promoters that combine elements of more than onepromoter. An expression construct may be present in a cell on anepisome, such as a plasmid, or the expression construct may be insertedin a chromosome. In a preferred embodiment, the expression vectorcontains a selectable marker gene to allow the selection of transformedhost cells. Selectable marker genes are well known in the art and willvary with the host cell used.

In certain aspect of the invention, the subject nucleic acid is providedin an expression vector comprising a nucleotide sequence encoding anEphB4 or Ephrin B2 soluble polypeptide and operably linked to at leastone regulatory sequence. Regulatory sequences are art-recognized and areselected to direct expression of the soluble polypeptide. Accordingly,the term regulatory sequence includes promoters, enhancers, and otherexpression control elements. Exemplary regulatory sequences aredescribed in Goeddel; Gene Expression Technology: Methods in Enzymology,Academic Press, San Diego, Calif. (1990). For instance, any of a widevariety of expression control sequences that control the expression of aDNA sequence when operatively linked to it may be used in these vectorsto express DNA sequences encoding a soluble polypeptide. Such usefulexpression control sequences, include, for example, the early and latepromoters of SV40, tet promoter, adenovirus or cytomegalovirus immediateearly promoter, the lac system, the trp system, the TAC or TRC system,T7 promoter whose expression is directed by T7 RNA polymerase, the majoroperator and promoter regions of phage lambda, the control regions forfd coat protein, the promoter for 3-phosphoglycerate kinase or otherglycolytic enzymes, the promoters of acid phosphatase, e.g., Pho5, thepromoters of the yeast a-mating factors, the polyhedron promoter of thebaculovirus system and other sequences known to control the expressionof genes of prokaryotic or eukaryotic cells or their viruses, andvarious combinations thereof. It should be understood that the design ofthe expression vector may depend on such factors as the choice of thehost cell to be transformed and/or the type of protein desired to beexpressed. Moreover, the vector's copy number, the ability to controlthat copy number and the expression of any other protein encoded by thevector, such as antibiotic markers, should also be considered.

This invention also pertains to a host cell transfected with arecombinant gene including a coding sequence for one or more of thesubject soluble polypeptide. The host cell may be any prokaryotic oreukaryotic cell. For example, a soluble polypeptide of the invention maybe expressed in bacterial cells such as E. coli, insect cells (e.g.,using a baculovirus expression system), yeast, or mammalian cells. Othersuitable host cells are known to those skilled in the art.

Accordingly, the present invention further pertains to methods ofproducing the subject soluble polypeptides. For example, a host celltransfected with an expression vector encoding an EphB4 solublepolypeptide can be cultured under appropriate conditions to allowexpression of the EphB4 soluble polypeptide to occur. The EphB4 solublepolypeptide may be secreted and isolated from a mixture of cells andmedium containing the soluble polypeptides. Alternatively, the solublepolypeptides may be retained cytoplasmically or in a membrane fractionand the cells harvested, lysed and the protein isolated. A cell cultureincludes host cells, media and other byproducts. Suitable media for cellculture are well known in the art. The soluble polypeptides can beisolated from cell culture medium, host cells, or both using techniquesknown in the art for purifying proteins, including ion-exchangechromatography, gel filtration chromatography, ultrafiltration,electrophoresis, and immunoaffinity purification with antibodiesspecific for particular epitopes of the soluble polypeptides. In apreferred embodiment, the soluble polypeptide is a fusion proteincontaining a domain which facilitates its purification.

A recombinant nucleic acid of the invention can be produced by ligatingthe cloned gene, or a portion thereof, into a vector suitable forexpression in either prokaryotic cells, eukaryotic cells (yeast, avian,insect or mammalian), or both. Expression vehicles for production of arecombinant soluble polypeptide include plasmids and other vectors. Forinstance, suitable vectors include plasmids of the types: pBR322-derivedplasmids, pEMBL-derived plasmids, pEX-derived plasmids, pBTac-derivedplasmids and pUC-derived plasmids for expression in prokaryotic cells,such as E. coli.

The preferred mammalian expression vectors contain both prokaryoticsequences to facilitate the propagation of the vector in bacteria, andone or more eukaryotic transcription units that are expressed ineukaryotic cells. The pcDNAI/amp, pcDNAI/neo, pRc/CMV, pSV2gpt, pSV2neo,pSV2-dhfr, pTk2, pRSVneo, pMSG, pSVT7, pko-neo and pHyg derived vectorsare examples of mammalian expression vectors suitable for transfectionof eukaryotic cells. Some of these vectors are modified with sequencesfrom bacterial plasmids, such as pBR322, to facilitate replication anddrug resistance selection in both prokaryotic and eukaryotic cells.Alternatively, derivatives of viruses such as the bovine papilloma virus(BPV-1), or Epstein-Barr virus (pHEBo, pREP-derived and p205) can beused for transient expression of proteins in eukaryotic cells. Examplesof other viral (including retroviral) expression systems can be foundbelow in the description of gene therapy delivery systems. The variousmethods employed in the preparation of the plasmids and transformationof host organisms are well known in the art. For other suitableexpression systems for both prokaryotic and eukaryotic cells, as well asgeneral recombinant procedures, see Molecular Cloning A LaboratoryManual, 2nd Ed., ed. by Sambrook, Fritsch and Maniatis (Cold SpringHarbor Laboratory Press, 1989) Chapters 16 and 17. In some instances, itmay be desirable to express the recombinant SLC5A8 polypeptide by theuse of a baculovirus expression system. Examples of such baculovirusexpression systems include pVL-derived vectors (such as pVL1392, pVL1393and pVL941), pAcUW-derived vectors (such as pAcUW1), andpBlueBac-derived vectors (such as the β-gal containing pBlueBac III).

Techniques for making fusion genes are well known. Essentially, thejoining of various DNA fragments coding for different polypeptidesequences is performed in accordance with conventional techniques,employing blunt-ended or stagger-ended termini for ligation, restrictionenzyme digestion to provide for appropriate termini, filling-in ofcohesive ends as appropriate, alkaline phosphatase treatment to avoidundesirable joining, and enzymatic ligation. In another embodiment, thefusion gene can be synthesized by conventional techniques includingautomated DNA synthesizers. Alternatively, PCR amplification of genefragments can be carried out using anchor primers which give rise tocomplementary overhangs between two consecutive gene fragments which cansubsequently be annealed to generate a chimeric gene sequence (see, forexample, Current Protocols in Molecular Biology, eds. Ausubel et al.,John Wiley & Sons: 1992).

IV. Antibodies

In certain aspects, the the present invention provides antagonistantibodies against Ephrin B2 or EphB4. As described herein, the term“antagonist antibody” refers to an antibody that inhibits function ofEphrin B2 or EphB4. Preferably, the antagonist antibody binds to anextracellular domain of Ephrin B2 or EphB4. It is understood thatantibodies of the invention may be polyclonal or monoclonal; intact ortruncated, e.g., F(ab′)2, Fab, Fv; xenogeneic, allogeneic, syngeneic, ormodified forms thereof, e.g., humanized, chimeric, etc.

For example, by using immunogens derived from an Ephrin B2 or EphB4polypeptide, anti-protein/anti-peptide antisera or monoclonal antibodiescan be made by standard protocols (see, for example, Antibodies: ALaboratory Manual ed. by Harlow and Lane (Cold Spring Harbor Press:1988)). A mammal, such as a mouse, a hamster or rabbit can be immunizedwith an immunogenic form of the peptide. (e.g., a polypeptide or anantigenic fragment which is capable of eliciting an antibody response,or a fusion protein). Techniques for conferring immunogenicity on aprotein or peptide include conjugation to carriers or other techniqueswell known in the art. An immunogenic portion of an Ephrin B2 or EphB4polypeptide can be administered in the presence of adjuvant. Theprogress of immunization can be monitored by detection of antibodytiters in plasma or serum. Standard ELISA or other immunoassays can beused with the immunogen as antigen to assess the levels of antibodies.In one embodiment, antibodies of the invention are specific for theextracellular portion of the Ephrin B2 or EphB4 protein. In anotherembodiment, antibodies of the invention are specific for theintracellular portion or the transmembrane portion of the Ephrin B2 orEphB4 protein. In a further embodiment, antibodies of the invention arespecific for the extracellular portion of the Ephrin B2 or EphB4protein.

Following immunization of an animal with an antigenic preparation of anEphrin B2 or EphB4 polypeptide, antisera can be obtained and, ifdesired, polyclonal antibodies can be isolated from the serum. Toproduce monoclonal antibodies, antibody-producing cells (lymphocytes)can be harvested from an immunized animal and fused by standard somaticcell fusion procedures with immortalizing cells such as myeloma cells toyield hybridoma cells. Such techniques are well known in the art, andinclude, for example, the hybridoma technique (originally developed byKohler and Milstein, (1975) Nature, 256: 495-497), the human B cellhybridoma technique (Kozbar et al., (1983) Immunology Today, 4: 72), andthe EBV-hybridoma technique to produce human monoclonal antibodies (Coleet al., (1985) Monoclonal Antibodies and Cancer Therapy, Alan R. Liss,Inc. pp. 77-96). Hybridoma cells can be screened immunochemically forproduction of antibodies specifically reactive with an Ephrin B2 orEphB4 polypeptide and monoclonal antibodies isolated from a culturecomprising such hybridoma cells.

The term antibody as used herein is intended to include fragmentsthereof which are also specifically reactive with an Ephrin B2 or EphB4polypeptides. Antibodies can be fragmented using conventional techniquesand the fragments screened for utility in the same manner as describedabove for whole antibodies. For example, F(ab)2 fragments can begenerated by treating antibody with pepsin. The resulting F(ab)2fragment can be treated to reduce disulfide bridges to produce Fabfragments. The antibody of the present invention is further intended toinclude bispecific, single-chain, and chimeric and humanized moleculeshaving affinity for an Ephrin B2 or EphB4 polypeptide conferred by atleast one CDR region of the antibody. Techniques for the production ofsingle chain antibodies (U.S. Pat. No. 4,946,778) can also be adapted toproduce single chain antibodies. Also, transgenic mice or otherorganisms including other mammals, may be used to express humanizedantibodies. In preferred embodiments, the antibodies further comprise alabel attached thereto and able to be detected (e.g., the label can be aradioisotope, fluorescent compound, enzyme or enzyme co-factor).

In certain preferred embodiments, an antibody of the invention is amonoclonal antibody, and in certain embodiments the invention makesavailable methods for generating novel antibodies. For example, a methodfor generating a monoclonal antibody that binds specifically to anEphrin B2 or EphB4 polypeptide may comprise administering to a mouse anamount of an immunogenic composition comprising the Ephrin B2 or EphB4polypeptide effective to stimulate a detectable immune response,obtaining antibody-producing cells (e.g., cells from the spleen) fromthe mouse and fusing the antibody-producing cells with myeloma cells toobtain antibody-producing hybridomas, and testing the antibody-producinghybridomas to identify a hybridoma that produces a monocolonal antibodythat binds specifically to the Ephrin B2 or EphB4 polypeptide. Onceobtained, a hybridoma can be propagated in a cell culture, optionally inculture conditions where the hybridoma-derived cells produce themonoclonal antibody that binds specifically to the Ephrin B2 or EphB4polypeptide. The monoclonal antibody may be purified from the cellculture.

In addition, the techniques used to screen antibodies in order toidentify a desirable antibody may influence the properties of theantibody obtained. For example, an antibody to be used for certaintherapeutic purposes will preferably be able to target a particular celltype. Accordingly, to obtain antibodies of this type, it may bedesirable to screen for antibodies that bind to cells that express theantigen of interest (e.g., by fluorescence activated cell sorting).Likewise, if an antibody is to be used for binding an antigen insolution, it may be desirable to test solution binding. A variety ofdifferent techniques are available for testing antibody:antigeninteractions to identify particularly desirable antibodies. Suchtechniques include ELISAs, surface plasmon resonance binding assays(e.g. the Biacore binding assay, Bia-core AB, Uppsala, Sweden), sandwichassays (e.g. the paramagnetic bead system of IGEN International, Inc.,Gaithersburg, Md.), western blots, immunoprecipitation assays andimmunohistochemistry.

V. Drug Screening Assays There are numerous approaches to screening forpolypeptide therapeutic agents as antagonists of EphB4, Ephrin B2 orboth. For example, high-throughput screening of compounds or moleculescan be carried out to identify agents or drugs which inhibitangiogenesis or inhibit tumor growth. Test agents can be any chemical(element, molecule, compound, drug), made synthetically, made byrecombinant techniques or isolated from a natural source. For example,test agents can be peptides, polypeptides, peptoids, sugars, hormones,or nucleic acid molecules. In addition, test agents can be smallmolecules or molecules of greater complexity made by combinatorialchemistry, for example, and compiled into libraries. These libraries cancomprise, for example, alcohols, alkyl halides, amines, amides, esters,aldehydes, ethers and other classes of organic compounds. Test agentscan also be natural or genetically engineered products isolated fromlysates or growth media of cells—bacterial, animal or plant—or can bethe cell lysates or growth media themselves. Presentation of testcompounds to the test system can be in either an isolated form or asmixtures of compounds, especially in initial screening steps.

For example, an assay can be carried out to screen for compounds thatspecifically inhibit binding of Ephrin B2 (ligand) to EphB4 (receptor),or vice-versa, e.g., by inhibition of binding of labeled ligand- orreceptor-Fc fusion proteins to immortalized cells. Compounds identifiedthrough this screening can then be tested in animals to assess theiranti-angiogenesis or anti-tumor activity in vivo.

In one embodiment of an assay to identify a substance that interfereswith interaction of two cell surface molecules (e.g., Ephrin B2 andEphB4), samples of cells expressing one type of cell surface molecule(e.g., EphB4) are contacted with either labeled ligand (e.g., Ephrin B2,or a soluble portion thereof, or a fusion protein such as a fusion ofthe extracellular domain and the Fc domain of IgG) or labeled ligandplus a test compound (or group of test compounds). The amount of labeledligand which has bound to the cells is determined. A lesser amount oflabel (where the label can be, for example, a radioactive isotope, afluorescent or colormetric label) in the sample contacted with the testcompound(s) is an indication that the test compound(s) interferes withbinding. The reciprocal assay using cells expressing a ligand (e.g., anEphrin B2 ligand or a soluble form thereof) can be used to test for asubstance that interferes with the binding of an Eph receptor or solubleportion thereof.

An assay to identify a substance which interferes with interactionbetween an Eph receptor and an ephrin can be performed with thecomponent (e.g., cells, purified protein, including fusion proteins andportions having binding activity) which is not to be in competition witha test compound, linked to a solid support. The solid support can be anysuitable solid phase or matrix, such as a bead, the wall of a plate orother suitable surface (e.g., a well of a microtiter plate), column poreglass (CPG) or a pin that can be submerged into a solution, such as in awell. Linkage of cells or purified protein to the solid support can beeither direct or through one or more linker molecules.

In one embodiment, an isolated or purified protein (e.g., an Ephreceptor or an ephrin) can be immobilized on a suitable affinity matrixby standard techniques, such as chemical cross-linking, or via anantibody raised against the isolated or purified protein, and bound to asolid support. The matrix can be packed in a column or other suitablecontainer and is contacted with one or more compounds (e.g., a mixture)to be tested under conditions suitable for binding of the compound tothe protein. For example, a solution containing compounds can be made toflow through the matrix. The matrix can be washed with a suitable washbuffer to remove unbound compounds and non-specifically bound compounds.Compounds which remain bound can be released by a suitable elutionbuffer. For example, a change in the ionic strength or pH of the elutionbuffer can lead to a release of compounds. Alternatively, the elutionbuffer can comprise a release component or components designed todisrupt binding of compounds (e.g., one or more ligands or receptors, asappropriate, or analogs thereof which can disrupt binding orcompetitively inhibit binding of test compound to the protein).

Fusion proteins comprising all, or a portion of, a protein (e.g., an Ephreceptor or an ephrin) linked to a second moiety not occurring in thatprotein as found in nature can be prepared for use in another embodimentof the method. Suitable fusion proteins for this purpose include thosein which the second moiety comprises an affinity ligand (e.g., anenzyme, antigen, epitope). The fusion proteins can be produced byinserting the protein (e.g., an Eph receptor or an ephrin) or a portionthereof into a suitable expression vector which encodes an affinityligand. The expression vector can be introduced into a suitable hostcell for expression. Host cells are disrupted and the cell material,containing fusion protein, can be bound to a suitable affinity matrix bycontacting the cell material with an affinity matrix under conditionssufficient for binding of the affinity ligand portion of the fusionprotein to the affinity matrix.

In one aspect of this embodiment, a fusion protein can be immobilized ona suitable affinity matrix under conditions sufficient to bind theaffinity ligand portion of the fusion protein to the matrix, and iscontacted with one or more compounds (e.g., a mixture) to be tested,under conditions suitable for binding of compounds to the receptor orligand protein portion of the bound fusion protein. Next, the affinitymatrix with bound fusion protein can be washed with a suitable washbuffer to remove unbound compounds and non-specifically bound compoundswithout significantly disrupting binding of specifically boundcompounds. Compounds which remain bound can be released by contactingthe affinity matrix having fusion protein bound thereto with a suitableelution buffer (a compound elution buffer). In this aspect, compoundelution buffer can be formulated to permit retention of the fusionprotein by the affinity matrix, but can be formulated to interfere withbinding of the compound(s) tested to the receptor or ligand proteinportion of the fusion protein. For example, a change in the ionicstrength or pH of the elution buffer can lead to release of compounds,or the elution buffer can comprise a release component or componentsdesigned to disrupt binding of compounds to the receptor or ligandprotein portion of the fusion protein (e.g., one or more ligands orreceptors or analogs thereof which can disrupt binding of compounds tothe receptor or ligand protein portion of the fusion protein).Immobilization can be performed prior to, simultaneous with, or aftercontacting the fusion protein with compound, as appropriate. Variouspermutations of the method are possible, depending upon factors such asthe compounds tested, the affinity matrix selected, and elution bufferformulation. For example, after the wash step, fusion protein withcompound bound thereto can be eluted from the affinity matrix with asuitable elution buffer (a matrix elution buffer). Where the fusionprotein comprises a cleavable linker, such as a thrombin cleavage site,cleavage from the affinity ligand can release a portion of the fusionwith compound bound thereto. Bound compound can then be released fromthe fusion protein or its cleavage product by an appropriate method,such as extraction.

VI. Methods of Treatment

In certain embodiments, the present invention provides methods ofinhibiting angiogenesis and methods of treating angiogenesis-associateddiseases. In other embodiments, the present invention provides methodsof inhibiting or reducing tumor growth and methods of treating anindividual suffering from cancer. These methods involve administering tothe individual a therapeutically effective amount of one or morepolypeptide therapeutic agents as described above. These methods areparticularly aimed at therapeutic and prophylactic treatments ofanimals, and more particularly, humans.

As described herein, angiogenesis-associated diseases include, but arenot limited to, angiogenesis-dependent cancer, including, for example,solid tumors, blood born tumors such as leukemias, and tumor metastases;benign tumors, for example hemangiomas, acoustic neuromas,neurofibromas, trachomas, and pyogenic granulomas; inflammatorydisorders such as immune and non-immune inflammation; chronic articularrheumatism and psoriasis; ocular angiogenic diseases, for example,diabetic retinopathy, retinopathy of prematurity, macular degeneration,corneal graft rejection, neovascular glaucoma, retrolental fibroplasia,rubeosis; Osler-Webber Syndrome; myocardial angiogenesis; plaqueneovascularization; telangiectasia; hemophiliac joints; angiofibroma;and wound granulation and wound healing; telangiectasia psoriasisscleroderma, pyogenic granuloma, cororany collaterals, ischemic limbangiogenesis, corneal diseases, rubeosis, arthritis, diabeticneovascularization, fractures, vasculogenesis, hematopoiesis.

It is understood that methods and compositions of the invention are alsouseful for treating any angiogenesis-independent cancers (tumors). Asused herein, the term “angiogenesis-independent cancer” refers to acancer (tumor) where there is no or little neovascularization in thetumor tissue.

In particular, polypeptide therapeutic agents of the present inventionare useful for treating or preventing a cancer (tumor), including, butnot limited to, colon carcinoma, breast cancer, mesothelioma, prostatecancer, bladder cancer, squamous cell carcinoma of the head and neck(HNSCC), Kaposi sarcoma, and leukemia.

In certain embodiments of such methods, one or more polypeptidetherapeutic agents can be administered, together (simultaneously) or atdifferent times (sequentially). In addition, polypeptide therapeuticagents can be administered with another type of compounds for treatingcancer or for inhibiting angiogenesis.

In certain embodiments, the subject methods of the invention can be usedalone. Alternatively, the subject methods may be used in combinationwith other conventional anti-cancer therapeutic approaches directed totreatment or prevention of proliferative disorders (e.g., tumor). Forexample, such methods can be used in prophylactic cancer prevention,prevention of cancer recurrence and metastases after surgery, and as anadjuvant of other conventional cancer therapy. The present inventionrecognizes that the effectiveness of conventional cancer therapies(e.g., chemotherapy, radiation therapy, phototherapy, immunotherapy, andsurgery) can be enhanced through the use of a subject polypeptidetherapeutic agent.

A wide array of conventional compounds have been shown to haveanti-neoplastic activities. These compounds have been used aspharmaceutical agents in chemotherapy to shrink solid tumors, preventmetastases and further growth, or decrease the number of malignant cellsin leukemic or bone marrow malignancies. Although chemotherapy has beeneffective in treating various types of malignancies, manyanti-neoplastic compounds induce undesirable side effects. It has beenshown that when two or more different treatments are combined, thetreatments may work synergistically and allow reduction of dosage ofeach of the treatments, thereby reducing the detrimental side effectsexerted by each compound at higher dosages. In other instances,malignancies that are refractory to a treatment may respond to acombination therapy of two or more different treatments.

When a polypeptide therapeutic agent of the present invention isadministered in combination with another conventional anti-neoplasticagent, either concomitantly or sequentially, such therapeutic agent isshown to enhance the therapeutic effect of the anti-neoplastic agent orovercome cellular resistance to such anti-neoplastic agent. This allowsdecrease of dosage of an anti-neoplastic agent, thereby reducing theundesirable side effects, or restores the effectiveness of ananti-neoplastic agent in resistant cells.

Pharmaceutical compounds that may be used for combinatory anti-tumortherapy include, merely to illustrate: aminoglutethimide, amsacrine,anastrozole, asparaginase, bcg, bicalutamide, bleomycin, buserelin,busulfan, campothecin, capecitabine, carboplatin, carmustine,chlorambucil, cisplatin, cladribine, clodronate, colchicine,cyclophosphamide, cyproterone, cytarabine, dacarbazine, dactinomycin,daunorubicin, dienestrol, diethylstilbestrol, docetaxel, doxorubicin,epirubicin, estradiol, estramustine, etoposide, exemestane, filgrastim,fludarabine, fludrocortisone, fluorouracil, fluoxymesterone, flutamide,gemcitabine, genistein, goserelin, hydroxyurea, idarubicin, ifosfamide,imatinib, interferon, irinotecan, ironotecan, letrozole, leucovorin,leuprolide, levamisole, lomustine, mechlorethamine, medroxyprogesterone,megestrol, melphalan, mercaptopurine, mesna, methotrexate, mitomycin,mitotane, mitoxantrone, nilutamide, nocodazole, octreotide, oxaliplatin,paclitaxel, pamidronate, pentostatin, plicamycin, porfimer,procarbazine, raltitrexed, rituximab, streptozocin, suramin, tamoxifen,temozolomide, teniposide, testosterone, thioguanine, thiotepa,titanocene dichloride, topotecan, trastuzumab, tretinoin, vinblastine,vincristine, vindesine, and vinorelbine.

These chemotherapeutic anti-tumor compounds may be categorized by theirmechanism of action into, for example, following groups:anti-metabolites/anti-cancer agents, such as pyrimidine analogs(5-fluorouracil, floxuridine, capecitabine, gemcitabine and cytarabine)and purine analogs, folate antagonists and related inhibitors(mercaptopurine, thioguanine, pentostatin and2-chlorodeoxyadenosine(cladribine)); antiproliferative/antiritoticagents including natural products such as vinca alkaloids(vinblastine,vincristine, and vinorelbine), microtubule disruptors such astaxane(paclitaxel, docetaxel), vincristin, vinblastin, nocodazole,epothilones and navelbine, epidipodophyllotoxins (etoposide,teniposide), DNA damaging agents (actinomycin, amsacrine,anthracyclines, bleomycin, busulfan, camptothecin, carboplatin,chlorambucil, cisplatin, cyclophosphamide, cytoxan, dactinomycin,daunorubicin, doxorubicin, epirubicin, hexamethylmelamineoxaliplatin,iphosphamide, melphalan, merchlorehtamine, mitomycin, mitoxantrone,nitrosourea, plicamycin, procarbazine, taxol, taxotere, teniposide,triethylenethiophosphoramide and etoposide (VP16)); antibiotics such asdactinomycin(actinomycin D), daunorubicin, doxorubicin(adriamycin),idarubicin, anthracyclines, mitoxantrone, bleomycins,plicamycin(mithramycin) and mitomycin; enzymes (L-asparaginase whichsystemically metabolizes L-asparagine and deprives cells which do nothave the capacity to synthesize their own asparagine); antiplateletagents; antiproliferative/antimitotic alkylating agents such as nitrogenmustards (mechlorethamine, cyclophosphamide and analogs, melphalan,chlorambucil), ethylenimines and methylmelamines(hexamethylmelamine andthiotepa), alkyl sulfonates-busulfan, nitrosoureas(carmustine (BCMJ) andanalogs, streptozocin), trazenes-dacarbazinine (DTIC);antiproliferative/antimitotic antimetabolites such as folic acid analogs(methotrexate); platinum coordination complexes (cisplatin,carboplatin), procarbazine, hydroxyurea, mitotane, aminoglutethimide;hormones, hormone analogs (estrogen, tamoxifen, goserelin, bicalutamide,nilutamide) and aromatase inhibitors (letrozole, anastrozole);anticoagulants(heparin, synthetic heparin salts and other inhibitors ofthrombin); fibrinolytic agents (such as tissue plasminogen activator,streptokinase and urokinase), aspirin, dipyridamole, ticlopidine,clopidogrel, abciximab; antimigratory agents; antisecretory agents(breveldin); immunosuppressives (cyclosporine, tacrolimus (FK-506),sirolimus(rapamycin), azathioprine, mycophenolate mofetil);anti-angiogenic compounds (TNP-470, genistein) and growth factorinhibitors (vascular endothelial growth factor (VEGF) inhibitors,fibroblast growth factor (FGF) inhibitors); angiotensin receptorblocker; nitric oxide donors; anti-sense oligonucleotides; antibodies(trastuzumab); cell cycle inhibitors and differentiation inducers(tretinoin); mTOR inhibitors, topoisomerase inhibitors(doxorubicin(adriamycin), amsacrine, camptothecin, daunorubicin,dactinomycin, eniposide, epirubicin, etoposide, idarubicin andmitoxantrone, topotecan, irinotecan), corticosteroids (cortisone,dexamethasone, hydrocortisone, methylpednisolone, prednisone, andprenisolone); growth factor signal transduction kinase inhibitors;mitochondrial dysfunction inducers and caspase activators; and chromatindisruptors.

In certain embodiments, pharmaceutical compounds that may be used forcombinatory anti-angiogenesis therapy include: (1) inhibitors of releaseof “angiogenic molecules,” such as bFGF (basic fibroblast growthfactor); (2) neutralizers of angiogenic molecules, such as an anti-βbFGFantibodies; and (3) inhibitors of endothelial cell response toangiogenic stimuli, including collagenase inhibitor, basement membraneturnover inhibitors, angiostatic steroids, fungal-derived angiogenesisinhibitors, platelet factor 4, thrombospondin, arthritis drugs such asD-penicillamine and gold thiomalate, vitamin D₃ analogs,alpha-interferon, and the like. For additional proposed inhibitors ofangiogenesis, see Blood et al., Bioch. Biophys. Acta., 1032:89-118(1990), Moses et al., Science, 248:1408-1410 (1990), Ingber et al., Lab.Invest., 59:44-51 (1988), and U.S. Pat. Nos. 5,092,885, 5,112,946,5,192,744, 5,202,352, and 6,573,256. In addition, there are a widevariety of compounds that can be used to inhibit angiogenesis, forexample, peptides or agents that block the VEGF-mediated angiogenesispathway, endostatin protein or derivatives, lysine binding fragments ofangiostatin, melanin or melanin-promoting compounds, plasminogenfragments (e.g., Kringles 1-3 of plasminogen), tropoin subunits,antagonists of vitronectin α_(v)β₃, peptides derived from Saposin B,antibiotics or analogs (e.g., tetracycline, or neomycin),dienogest-containing compositions, compounds comprising a MetAP-2inhibitory core coupled to a peptide, the compound EM-138, chalcone andits analogs, and naaladase inhibitors. See, for example, U.S. Pat. Nos.6,395,718, 6,462,075, 6,465,431, 6,475,784, 6,482,802, 6,482,810,6,500,431, 6,500,924, 6,518,298, 6,521,439, 6,525,019, 6,538,103,6,544,758, 6,544,947, 6,548,477, 6,559,126, and 6,569,845.

Depending on the nature of the combinatory therapy, administration ofthe polypeptide therapeutic agents of the invention may be continuedwhile the other therapy is being administered and/or thereafter.Administration of the polypeptide therapeutic agents may be made in asingle dose, or in multiple doses. In some instances, administration ofthe polypeptide therapeutic agents is commenced at least several daysprior to the conventional therapy, while in other instances,administration is begun either immediately before or at the time of theadministration of the conventional therapy.

VI. Methods ofAdministration and Pharmaceutical Compositions

In certain embodiments, the subject polypeptide therapeutic agents(e.g., soluble polypeptides or antibodies) of the present invention areformulated with a pharmaceutically acceptable carrier. Such therapeuticagents can be administered alone or as a component of a pharmaceuticalformulation (composition). The compounds may be formulated foradministration in any convenient way for use in human or veterinarymedicine. Wetting agents, emulsifiers and lubricants, such as sodiumlauryl sulfate and magnesium stearate, as well as coloring agents,release agents, coating agents, sweetening, flavoring and perfumingagents, preservatives and antioxidants can also be present in thecompositions.

Formulations of the subject polypeptide therapeutic agents include thosesuitable for oral/ nasal, topical, parenteral, rectal, and/orintravaginal administration. The formulations may conveniently bepresented in unit dosage form and may be prepared by any methods wellknown in the art of pharmacy. The amount of active ingredient which canbe combined with a carrier material to produce a single dosage form willvary depending upon the host being treated, the particular mode ofadministration. The amount of active ingredient which can be combinedwith a carrier material to produce a single dosage form will generallybe that amount of the compound which produces a therapeutic effect.

In certain embodiments, methods of preparing these formulations orcompositions include combining another type of anti-tumor oranti-angiogenesis therapeutic agent and a carrier and, optionally, oneor more accessory ingredients. In general, the formulations can beprepared with a liquid carrier, or a finely divided solid carrier, orboth, and then, if necessary, shaping the product.

Formulations for oral administration may be in the form of capsules,cachets, pills, tablets, lozenges (using a flavored basis, usuallysucrose and acacia or tragacanth), powders, granules, or as a solutionor a suspension in an aqueous or non-aqueous liquid, or as anoil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup,or as pastilles (using an inert base, such as gelatin and glycerin, orsucrose and acacia) and/or as mouth washes and the like, each containinga predetermined amount of a subject polypeptide therapeutic agent as anactive ingredient.

In solid dosage forms for oral administration (capsules, tablets, pills,dragees, powders, granules, and the like), one or more polypeptidetherapeutic agents of the present invention may be mixed with one ormore pharmaceutically acceptable carriers, such as sodium citrate ordicalcium phosphate, and/or any of the following: (1) fillers orextenders, such as starches, lactose, sucrose, glucose, mannitol, and/orsilicic acid; (2) binders, such as, for example, carboxymethylcellulose,alginates, gelatin, polyvinyl pyrrolidone, sucrose, and/or acacia; (3)humectants, such as glycerol; (4) disintegrating agents, such asagar-agar, calcium carbonate, potato or tapioca starch, alginic acid,certain silicates, and sodium carbonate; (5) solution retarding agents,such as paraffin; (6) absorption accelerators, such as quaternaryammonium compounds; (7) wetting agents, such as, for example, cetylalcohol and glycerol monostearate; (8) absorbents, such as kaolin andbentonite clay; (9) lubricants, such a talc, calcium stearate, magnesiumstearate, solid polyethylene glycols, sodium lauryl sulfate, andmixtures thereof; and (10) coloring agents. In the case of capsules,tablets and pills, the pharmaceutical compositions may also comprisebuffering agents. Solid compositions of a similar type may also beemployed as fillers in soft and hard-filled gelatin capsules using suchexcipients as lactose or milk sugars, as well as high molecular weightpolyethylene glycols and the like.

Liquid dosage forms for oral administration include pharmaceuticallyacceptable emulsions, microemulsions, solutions, suspensions, syrups,and elixirs. In addition to the active ingredient, the liquid dosageforms may contain inert diluents commonly used in the art, such as wateror other solvents, solubilizing agents and emulsifiers, such as ethylalcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzylalcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils(in particular, cottonseed, groundnut, corn, germ, olive, castor, andsesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycolsand fatty acid esters of sorbitan, and mixtures thereof. Besides inertdiluents, the oral compositions can also include adjuvants such aswetting agents, emulsifying and suspending agents, sweetening,flavoring, coloring, perfuming, and preservative agents.

Suspensions, in addition to the active compounds, may contain suspendingagents such as ethoxylated isostearyl alcohols, polyoxyethylenesorbitol, and sorbitan esters, microcrystalline cellulose, aluminummetahydroxide, bentonite, agar-agar and tragacanth, and mixturesthereof.

In particular, methods of the invention can be administered topically,either to skin or to mucosal membranes such as those on the cervix andvagina. This offers the greatest opportunity for direct delivery totumor with the lowest chance of inducing side effects. The topicalformulations may further include one or more of the wide variety ofagents known to be effective as skin or stratum corneum penetrationenhancers. Examples of these are 2-pyrrolidone, N-methyl-2-pyrrolidone,dimethylacetamide, dimethylformamide, propylene glycol, methyl orisopropyl alcohol, dimethyl sulfoxide, and azone. Additional agents mayfurther be included to make the formulation cosmetically acceptable.Examples of these are fats, waxes, oils, dyes, fragrances,preservatives, stabilizers, and surface active agents. Keratolyticagents such as those known in the art may also be included. Examples aresalicylic acid and sulfur.

Dosage forms for the topical or transdermal administration includepowders, sprays, ointments, pastes, creams, lotions, gels, solutions,patches, and inhalants. The subject polypeptide therapeutic agents maybe mixed under sterile conditions with a pharmaceutically acceptablecarrier, and with any preservatives, buffers, or propellants which maybe required. The ointments, pastes, creams and gels may contain, inaddition to a subject polypeptide agent, excipients, such as animal andvegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulosederivatives, polyethylene glycols, silicones, bentonites, silicic acid,talc and zinc oxide, or mixtures thereof.

Powders and sprays can contain, in addition to a subject polypeptidetherapeutic agent, excipients such as lactose, talc, silicic acid,aluminum hydroxide, calcium silicates, and polyamide powder, or mixturesof these substances. Sprays can additionally contain customarypropellants, such as chlorofluorohydrocarbons and volatile unsubstitutedhydrocarbons, such as butane and propane.

Pharmaceutical compositions suitable for parenteral administration maycomprise one or more polypeptide therapeutic agents in combination withone or more pharmaceutically acceptable sterile isotonic aqueous ornonaqueous solutions, dispersions, suspensions or emulsions, or sterilepowders which may be reconstituted into sterile injectable solutions ordispersions just prior to use, which may contain antioxidants, buffers,bacteriostats, solutes which render the formulation isotonic with theblood of the intended recipient or suspending or thickening agents.Examples of suitable aqueous and nonaqueous carriers which may beemployed in the pharmaceutical compositions of the invention includewater, ethanol, polyols (such as glycerol, propylene glycol,polyethylene glycol, and the like), and suitable mixtures thereof,vegetable oils, such as olive oil, and injectable organic esters, suchas ethyl oleate. Proper fluidity can be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants.

These compositions may also contain adjuvants, such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofthe action of microorganisms may be ensured by the inclusion of variousantibacterial and antifungal agents, for example, paraben,chlorobutanol, phenol sorbic acid, and the like. It may also bedesirable to include isotonic agents, such as sugars, sodium chloride,and the like into the compositions. In addition, prolonged absorption ofthe injectable pharmaceutical form may be brought about by the inclusionof agents which delay absorption, such as aluminum monostearate andgelatin.

Injectable depot forms are made by forming microencapsule matrices ofone or more polypeptide therapeutic agents in biodegradable polymerssuch as polylactide-polyglycolide. Depending on the ratio of drug topolymer, and the nature of the particular polymer employed, the rate ofdrug release can be controlled. Examples of other biodegradable polymersinclude poly(orthoesters) and poly(anhydrides). Depot injectableformulations are also prepared by entrapping the drug in liposomes ormicroemulsions which are compatible with body tissue.

Formulations for intravaginal or rectally administration may bepresented as a: suppository, which may be prepared by mixing one or morecompounds of the invention with one or more suitable nonirritatingexcipients or carriers comprising, for example, cocoa butter,polyethylene glycol, a suppository wax or a salicylate, and which issolid at room temperature, but liquid at body temperature and,therefore, will melt in the rectum or vaginal cavity and release theactive compound.

In other embodiments, the polypeptide therapeutic agents of the instantinvention can be expressed within cells from eukaryotic promoters. Forexample, a soluble polypeptide of EphB4 or Ephrin B2 can be expressed ineukaryotic cells from an appropriate vector. The vectors are preferablyDNA plasmids or viral vectors. Viral vectors can be constructed basedon, but not limited to, adeno-associated virus, retrovirus, adenovirus,or alphavirus. Preferably, the vectors stably introduced in and persistin target cells. Alternatively, viral vectors can be used that providefor transient expression. Such vectors can be repeatedly administered asnecessary. Delivery of vectors encoding the subject polypeptidetherapeutic agent can be systemic, such as by intravenous orintramuscular administration, by administration to target cellsex-planted from the patient followed by reintroduction into the patient,or by any other means that would allow for introduction into the desiredtarget cell (for a review see Couture et al., 1996, TIG., 12, 510).

Exemplification

The invention now being generally described, it will be more readilyunderstood by reference to the following examples, which are includedmerely for purposes of illustration of certain aspects and embodimentsof the present invention, and are not intended to limit the invention.

EXAMPLE 1 Soluble Derivatives of the Extracellular Domains of HumanEphrin B2 and EphB4 Proteins

Soluble derivatives of the extracellular domains of human Ephrin B2 andEphB4 proteins represent either truncated full-length predictedextracellular domains of Ephrin B2 (B4ECv3, B2EC) or translationalfusions of the domains with constant region of human immunoglobulins(IgG1 Fc fragment), such as B2EC-FC, B4ECv2-FC and B4ECv3-FC.Representative human Ephrin B2 constructs and human EphB4 constructs areshown FIGS. 14 and 15.

The cDNA fragments encoding these recombinant proteins were subclonedinto mammalian expression vectors, expressed in transiently or stablytransfected mammalian cell lines and purified to homogeneity asdescribed in detail in Materials and Methods section (see below).Predicted amino acid sequences of the proteins are shown in FIGS. 1-5.High purity of the isolated proteins and their recognition by thecorresponding anti-Ephrin B2 and anti-EphB4 monoclonal or polyclonalantibodies were confirmed. The recombinant proteins exhibit the expectedhigh-affinity binding, binding competition and specificity propertieswith their corresponding binding partners as corroborated by thebiochemical assays (see e.g., FIGS. 6-8).

Such soluble derivative proteins human Ephrin B2 and EphB4 exhibitpotent biological activity in several cell-based assays and in vivoassays which measure angiogenesis or anti-cancer activities, and aretherefore perspective drug candidates for anti-angiogenic andanti-cancer therapy. B4ECv3 as well as B2EC and B2EC-FC proteins blockedchemotaxis of human endothelial cells (as tested with umbilical cord andhepatic AECs or VECs), with a decrease in degradation of theextracellular matrix, Matrigel, and a decrease in migration in responseto growth factor stimuli (FIGS. 9-11). B4ECv3 and B2EC-FC proteins havepotent anti-angiogenic effect as demonstrated by their inhibition ofendothelial cell tube formation (FIGS. 12-13).

Materials and Methods

1) Mammalian Expression Vectors for Producing Recombinant SolubleDerivatives of Ephrin B2 and Eph B4

Plasmids vectors for expressing recombinant soluble derivatives ofEphrin B2 and EphB4 were based on pEF6/V5-His-TOPO vector (Invitrogen),pIG (Novagen) or pRK5. pEF6/V5-His-TOPO contains human elongation factor1 a enhancer/promoter and blasticidin resistance marker. pIG vector isdesigned for high-level expression of protein fusions with Fc portion ofhuman IgG1under CMV promoter control and pRK5 is a general purpose CMVpromoter-containing mammalian expression vector. To generate plasmidconstruct pEF6-B4EC-NT, cDNA fragment of human EphB4 was amplified byPCR using oligo primers 5′-GGATCCGCC ATGGAGCTC CGGGTGCTGCT-3′ and5′-TGGATCCCT GCTCCCGC CAGCCCTCG CTCTCATCCA-3′, and TOPO-cloned intopEF6/V5-His-TOPO vector. pEF6-hB4ECv3 was derived from pEF6-B4ECNT bydigesting the plasmid DNA with EcoRV and BstBI, filling-in the ends withKlenow enzyme and religating the vector. Recombinant EphB4 derivativeencoded by pEF6-B4EC-NT does not contain epitope- or purification tags,while the similar B4ECv3 protein encoded by pEF6-hB4ECv3 contains V5epitope tag and 6×His tag on its C-terminus to facilitate purificationfrom conditioned media. Plasmid construct pEF6-hB2EC was created by PCRamplification of Ephrin B2 cDNA using oligo primers 5′-TGGATCCACCATGGCTGT GAGAAGGGAC-3′ plus 5′-ATTAATGGTGATGGT GAT GATGACTAC CCACTTCGGAACCGAGGATGTTGTTC-3′ and TOPO-cloning into pEF6/V5-His-TOPO vector.Plasmid construct pIG-hB2EC-FC was created by PCR amplification ofEphrin B2 cDNA with oligo primers 5′-TAAAGCTTCCGCCATGG CTGTGAGAAGGGAC-3′and 5′-TAGGATCCACTTCGGA ACCGAGGATGTTGTT CCC-3′, followed by TOPO-cloningand sequencing the resulting PCR fragment with consecutive subcloning inpIG hIgG1Fc fusion expression vector cut with Bam HI and Hind III.Similarly, pIG-hB2EC and pIG-hB4ECv3 were generated by PCR amplifyingportions of EphB4 ECD cDNA using oligo primers 5′-ATAAGCTTCC GCCATGGAGCTCCGGGTGCTG-3′ plus 5′-TTGGATCCTGCTCCCG CCAGCCCTCGC TCTCATC-3′ withconsecutive subcloning into pIG hIgG1 Fc fusion expression vector cutwith Bam HI and Hind III. Predicted sequences of the proteins encoded bythe vectors described above are shown in FIGS. 1-5.

2) Mammalian Cell Culture and Transfections

HEK293T (human embryonic kidney line) cells were maintained in DMEM with10% dialyzed fetal calf serum and 1% penicillin/streptomycin/neomycinantibiotics. Cells were maintained at 37° C. in a humidified atmosphereof 5% CO₂/95% air. Transfections were performed using Lipofectamine 2000reagent (Invitrogen) according to the manufacturer's protocol. One daybefore transfections, 293T cells were seeded at a high density to reach80% confluence at the time of transfection. Plasmid DNA andLipofectamine reagent at 1:3 ratio were diluted in Opti-MEM I reducedserum medium (Invitrogen) for 5 min and mixed together to formDNA:Lipofectamine complex. For each 10 cm culture dish, 10 μg of plasmidDNA was used. After 20 min, above complex was added directly to cells inculture medium. After 16 hours of transfection, medium was aspirated,washed once with serum free DMEM and replaced with serum free DMEM.Secreted proteins were harvested after 48 hours by collectingconditional medium. Conditional medium was clarified by centrifugationat 10,000 g for 20 min, filtered through 0.2 μm filter and used forpurification.

3) Generating Stable Cell Lines

To create stable cell lines producing EphB4ECv3 and EphB4ECnt BEK293 orHEK293T cells were transfected with either pEF6-B4ECv3 or pEF6-B4EC-NTplasmid constructs as described above and selected using antibioticBlasticidin. After 24 hours of transfection, cells were seeded at lowdensity. Next day, cells were treated with 10 μg/ml of Blasticidin.After two weeks of drug selection, surviving cells were pooled andselected further for single cell clone expansion. After establishingstable cells, they were maintained at 4 μg/ml Blasticidin. Conditionedmedia were tested to confirm expression and secretion of the respectiverecombinant proteins. Specificity of expression was confirmed by Westernblot with anti-B4 mono- or polyclonal ABs and B2EC-AP reagent bindingand competition assays.

4) Protein Purification

HEK293 cells were transiently transfected with a plasmid encodingsecreted form of EphB4ectodomain (B4ECv3). Conditional media washarvested and supplemented with 10 mM imidazole, 0.3 M NaCl andcentrifuged at 20,000 g for 30 min to remove cell debris and insolubleparticles. 80 ml of obtained supernatant were applied onto thepre-equilibrated column with 1 ml of Ni—NTA-agarose (Qiagen) at the flowrate of 10 ml/h. After washing the column with 10 ml of 50 mM Tris-HCl,0.3 M NaCl and 10 mM imidazole, pH 8, remaining proteins were elutedwith 3 ml of 0.25 M imidazole. Eluted proteins were dialyzed against 20mM Tris-HCl, 0.15 M NaCl, pH 8 overnight. Purity and identity of B4ECv3was verified by PAGE/Coomassie G-250 and Western blot with anti-EphB4antibody. Finally, the concentration of B4ECv3 was measured, and theprotein was aliquoted and stored at −70° C.

B4EC-FC protein and B2EC-FC protein were similarly purified.

5) Biochemical Assays

A. Ending Assay

10 μl of Ni—NTA-Agarose were incubated in microcentrifuge tubes with 50μl of indicated amount of B4ECv3 diluted in binding buffer BB (20 mMTris-HCl, 0.15 M NaCl, 0.1% bovine serum albumin pH 8) After incubationfor 30 min on shaking platform, Ni—NTA beads were washed twice with 1.4ml of BB, followed by application of 50 μl of B2-AP in the finalconcentration of 50 nM. Binding was performed for 30 min on shakingplatform, and then tubes were centrifuged and washed one time with 1.4ml of BB. Amount of precipitated AP was measured calorimetrically afterapplication of PNPP.

B. Inhibition Assay

Inhibition in solution. Different amounts of B4ECv3 diluted in 50 μl ofBB were pre-incubated with 50 μl of 5 mM B2EC-AP reagent (protein fusionof Ephrin B2 ectodomain with placental alkaline phosphatase). Afterincubation for 1 h, unbound B2EC-AP was precipitated with 5,000 HEK293cells expressing membrane-associated full-length EphB4 for 20 min.Binding reaction was stopped by dilution with 1.2 ml of BB, followed bycentrifugation for 10 min. Supernatants were discarded and alkalinephosphatase activities associated with collected cells were measured byadding para-nitrophenyl phosphate (PNPP) substrate.

Cell based inhibition. B4ECv3 was serially diluted in 20 mM Tris-HCl,0.15 M NaCl, 0.1% BSA, pH 8 and mixed with 5,000 HEK293 cells expressingmembrane-associated full-length Ephrin B2. After incubation for 1 h, 50μl of 5 nM B4EC-AP reagent (protein fusion of EphB4 ectodomain withplacental alkaline phosphatase were added into each tube for 30 min todetect unoccupied Ephrin B2 binding sites. Binding reactions werestopped by dilution with 1.2 ml of BB and centrifugation. Colorimetricreaction of cell-precipitated AP was developed with PNPP substrate.

C. B4EC-FC Binding Assay

Protein A-agarose based assay. 10 μl of Protein A-agarose were incubatedin Eppendorf tubes with 50 μl of indicated amount of B4EC-FC diluted inbinding buffer BB (20 mM Tris-HCl, 0.15 M NaCl, 0.1% BSA pH 8). Afterincubation for 30 min on shaking platform, Protein Aagarose beads werewashed twice with 1.4 ml of BB, followed by application of 50 μl ofB2ECAP reagent at the final concentration of 50 nM. Binding wasperformed for 30 min on shaking platform, and then tubes werecentrifuged and washed once with 1.4 ml of BB. Colorimetric reaction ofprecipitated AP was measured after application of PNPP (FIG. 6).

Nitrocellulose based assay. B4EC-FC was serially diluted in 20 mMTris-HCl, 0.15 M NaCl, 50 μg/ml BSA, pH 8.2 μl of each fraction wereapplied onto nitrocellulose strip and spots were dried out for 3 min.Nitrocellulose strip was blocked with 5% non-fat milk for 30 min,followed by incubation with 5 nM B2EC-AP reagent. After 45 minincubation for binding, nitrocellulose was washed twice with 20 mMTris-HCl, 0.15 M NaCl, 50 μg/ml BSA, pH 8 and color was developed byapplication of alkaline phosphatase substrate Sigma Fast (Sigma).

D. B4EC-FC Inhibition Assay

Inhibition in solution. See above, for B4ECv3. The results were shown inFIG. 7.

Cell based inhibition. See above, for B4ECv3.

E. B2EC-FC Binding Assay

Protein-A-agarose based assay. See above, for B4EC-FC. The results wereshown in FIG. 8.

Nitrocellulose based assay. See above, for B4EC-FC. 6) Cell-Based Assays

A. Growth Inhibition Assay

Human umbilical cord vein endothelial cells (HUVEC) (1.5×103) are platedin a 96-well plate in 100 μl of EBM-2 (Clonetic # CC3162). After 24hours (day 0), the test recombinant protein (100 μl) is added to eachwell at 2× the desired concentration (5-7 concentration levels) in EBM-2medium. On day 0, one plate is stained with 0.5% crystal violet in 20%methanol for 10 minutes, rinsed with water, and air-dried. The remainingplates are incubated for 72 h at 37° C. After 72 h, plates are stainedwith 0:5% crystal violet in 20% methanol, rinsed with water andairdried. The stain is eluted with 1:1 solution of ethanol: 0.1 M sodiumcitrate (including day 0 plate), and absorbance is measured at 540 nmwith an ELISA reader (Dynatech Laboratories). Day 0 absorbance issubtracted from the 72 h plates and data is plotted as percentage ofcontrol proliferation (vehicle treated cells). IC50 (drug concentrationcausing 50% inhibition) is calculated from the plotted data.

B. Cord Formation Assay (Endothelial Cell Tube Formation Assay)

Matrigel (60 μl of 10 mg/ml; Collaborative Lab # 35423) is placed ineach well of an ice-cold 96-well plate. The plate is allowed to sit atroom temperature for 15 minutes then incubated at 37° C. for 30 minutesto permit the matrigel to polymerize. In the mean time, HUVECs areprepared in EGM-2 (Clonetic # CC3162) at a concentration of 2×10⁵cells/ml. The test compound is prepared at 2× the desired concentration(5 concentration levels) in the same medium. Cells (500 μl) and 2× drug(500 μl) is mixed and 200 μl of this suspension are placed in duplicateon the polymerized matrigel. After 24 h incubation, triplicate picturesare taken for each concentration using a Bioquant Image Analysis system.Drug effect (IC50) is assessed compared to untreated controls bymeasuring the length of cords formed and number of junctions.

C. Cell Migration Assay

Migration is assessed using the 48-well Boyden chamber and 8 μm poresize collagen-coated (10 μg/ml rat tail collagen; CollaborativeLaboratories) polycarbonate filters (Osmonics, Inc.). The bottom chamberwells receive 27-29 μl of DMEM medium alone (baseline) or mediumcontaining chemo-attractant (bFGF, VEGF or Swiss 3T3 cell conditionedmedium). The top chambers receive 45 μl of HLUVEC cell suspension (1×10⁶cells/ml) prepared in DMEM+1% BSA with or without test compound. After 5h incubation at 37° C., the membrane is rinsed in PBS, fixed and stainedin Diff-Quick solutions. The filter is placed on a glass slide with themigrated cells facing down and cells on top are removed using a Kimwipe.The testing is performed in 4-6 replicates and five fields are countedfrom each well. Negative unstimulated control values are subtracted fromstimulated control and drug treated values and data is plotted as meanmigrated cell±S.D. IC50 is calculated from the plotted data.

EXAMPLE 2 Extracellular Domain Fragments of EphB4 Receptor InhibitAngiogenesis and Tumor Growth

A. Globular Domain of EphB4 is Required for EphrinB2 Binding and for theActivity of EphB4-Derived Soluble Proteins in Endothelial Tube FormationAssay

To identify subdomain(s) of the ectopic part of EphB4 necessary andsufficient for the anti-angiogenic activity of the soluble recombinantderivatives of the receptor, four recombinant deletion variants ofEphB4EC were produced and tested (FIG. 16). Extracellular part of EphB4,similarly to the other members of EphB and EphA receptor family,contains N-terminal ligand-binding globular domain followed bycysteine-rich domain and two fibronectin type III repeats (FNII). Inaddition to the recombinant B4-GCF2 protein containing the completeectopic part of EphB4, we constructed three deletion variants of EphB4ECcontaining globular domain and Cys-rich domain (B4-GC); globular,Cys-rich and the first FNIII domain (GCF1) as well as the ECD versionwith deleted globular domain (CF2). Our attempts to produce severalversions of truncated EphB4EC protein containing the globular domainalone were not successful due to the lack of secretion of proteinsexpressed from all these constructs and absence of ligand binding by theintracellularly expressed recombinant proteins. In addition, anon-tagged version of B4-GCF2, called GCF2-F, containing completeextracellular domain of EphB4 with no additional fused amino acids wasexpressed, purified and used in some of the experiments described here.

All four C-terminally 6×His tagged recombinant proteins werepreparatively expressed in transiently transfected cultured mammaliancells and affinity purified to homogeneity from the conditioned growthmedia using chromatography on Ni²⁺-chelate resin (FIG. 17). Apparentlydue to their glycosylation, the proteins migrate on SDS-PAAG somewhathigher than suggested by their predicted molecular weights of 34.7 kDa(GC), 41.5 (CF2), 45.6 kDa (GCF1) and 57.8 kDa (GCF2). Sequence of theextracellular domain of human EphB4 contains three predictedN-glycosylation sites (NXS/T) which are located in the Cys-rich domain,within the first fibronectin type III repeat and between the first andthe second fibronectin repeats.

To confirm ability of the purified recombinant proteins to bind EphrinB2, they were tested in an in vitro binding assay. As expected, GC, GCF1and GCF2, but not CF2 are binding the cognate ligand Ephrin B2 asconfirmed by interaction between Ephrin B2—alkaline phosphatase (EphrinB2-AP) fusion protein with the B4 proteins immobilized on Ni²⁺⁻resin oron nitrocellulose membrane (FIG. 17).

All four proteins were also tested for their ability to blockligand-dependent dimerization and activation of Eph B4 receptor kinasein PC3 cells. The PC3 human prostate cancer cell line is known toexpress elevated levels of human Eph B4. Stimulation of PC3 cells withEphrin B2 IgG Fc fusion protein leads to a rapid induction of tyrosinephosphorylation of the receptor. However, preincubation of the ligandwith GCF2, GCF1 or GC, but not CF2 proteins suppresses subsequent EphB4autophosphorylation. Addition of the proteins alone to the PC3 cells orpreincubation of the cells with the proteins followed by changing mediaand adding the ligand does not affect EphB4 phosphorylation status.

Further, we found that globular domain of EphB4 is required for theactivity of EphB4-derived soluble proteins in endothelial tube formationassay.

B. Effects of Soluble EphB4 on HUJV/AEC in Vitro.

Initial experiments were performed to determine whether soluble EphB4affected the three main stages in the angiogenesis pathway. These werecarried out by establishing the effects of soluble EphB4 onmigration/invasion, proliferation and tubule formation by HUV/AEC invitro. Exposure to soluble EphB4 significantly inhibited both bFGF andVEGF-induced migration in the Boyden chamber assay in a dose-dependentmanner, achieving significance at nM (FIG. 18). Tubule formation byHUV/AECS on wells coated with Matrigel was significantly inhibited bysoluble EphB4 in a dose-dependent manner in both the absence andpresence of bFGF and VEGF (FIG. 19). We also assessed in vitro, whethermM of soluble EphB4 was cytotoxic for HUVECS. Soluble EphB4 was found tohave no detectable cytotoxic effect at these doses, as assessed by MTSassay (FIG. 20).

C. Soluble EphB4 Receptor Inhibits Vascularization of Matrigel Plugs, invivo

To demonstrate that soluble EphB4 can directly inhibit angiogenesis invivo, we performed a murine matrigel plug experiment. Matrigelsupplemented with bFGF and VEGF with and without soluble EphB4 wasinjected s.c. into Balb/C nu/nu mice, forming semi-solid plugs, for sixdays. Plugs without growth factors had virtually no vascularization orvessel structures after 6 days (FIG. 21). In contrast, plugssupplemented with bFGF and VEGF had extensive vascularization andvessels throughout the plug. Plugs taken from mice treated with μg ofsoluble EphB4 had markedly reduced vascularization of plugs, comparableto plugs without growth factor (FIG. 21). Furthermore, histologicalexamination of plugs showed decreased vessel staining (FIG. 21).Treatment at 0 μg/dose significantly inhibited the amount ofinfiltration in Matrigel plugs compared to control (FIG. 21).

We examined EphB4 receptor phosphorylation in HTVECs by performingWestern blot analyses with lysates from soluble EphB4-treated cells andantibodies against phosphor-tyrosine. We found that soluble EphB4treatment of serum-starved HLTVECs stimulated a rapid and transientdecrease in the level of phosphorylated EphB4, in the presence ofEphrinB2Fc, EphB4 ligand dimer. Ephrin B2Fc without the soluble EphB4protein induced phosphorylation of EphB4 receptor (FIG. 22).

D. Effects of Soluble EphB4 on Tumor Growth, in vitro.

We found that soluble EphB4 inhibits the growth of SCC15 tumors grown inBalb/C Nu/Nu mice (FIG. 23).

E. Soluble EphB4 Inhibited Corneal Neovascularization

To further investigate the antiangiogenic activity of soluble EphB4 invivo, we studied the inhibitory effect of administration of solubleEphB4 on neovascularization in the mouse cornea induced by bFGF. HydronPellets implanted into corneal micropocket could induce angiogenesis, inthe presence of growth factors, in a typically avascular area. Theangiogenesis response in mice cornea was moderate, the appearance ofvascular buds was delayed and the new capillaries were sparse and grewslowly. Compared with the control group, on day 7 of implantation, theneovascularization induced by bFGF in mice cornea was markedly inhibitedin soluble EphB4-treated group (FIG. 24).

F. Effects of Soluble EphB4 on Tumor Growth, in vivo.

The same model was used to determine the effects of soluble EphB4 invivo. SCC15 tumors implanted subcutaneously, pre-incubated with matrigeland with or w/o growth factors, as well as implanted sc alone, and micetreated sc or ip daily with 1-5 ug of soluble EphB4 were carried out.

Tumors in the control group continued to grow steadily over thetreatment period, reaching a final tumor volume of mmm³. However,animals injected with soluble EphB4 exhibited a significantly (p<0.0/)reduced growth rate, reaching a final tumor volume of only mm3 (FIG.25). Similar results were obtained in two further cohorts of suchtumor-bearing mice. Soluble EphB4 administration appeared to be welltolerated in vivo, with no significant effect on body weight or thegeneral well-being of the animals (as determined by the absence oflethargy, intermittent hunching, tremors or disturbed breathingpatterns).

G. Effects of Soluble EphB4 on Tumor Histology.

Histological analysis revealed the presence of a central area ofnecrosis in all SCC15 tumors, which was usually surrounded by a viablerim of tumor cells um in width. The central necrotic areas werefrequently large and confluent and showed loss of cellular detail.Necrosis, assessed as a percentage of tumor section area, wassignificantly (p<0.02) more extensive in the soluble EphB4-treated group(% necrosis in treated vs. control). To determine whether the reducedvolume of soluble EphB4 treated tumors was due to an effect of thisprotein on the tumor vascular supply, endothelial cells in blood vesselswere identified in tumor sections using immunostaining with ananti-platelet cell adhesion molecule (PECAM-1; CD31) antibody (FIG. 26)and the density of microvessels was assessed. Microvessel density wassimilar in the outer viable rim of tumor cells (the uniform layer ofcells adjacent to the tumor periphery with well defined nuclei) incontrol and soluble EphB4-treated tumors. Microvessel density wassignificantly in the inner, less viable region of tumor cells abuttingthe necrotic central areas in soluble EphB4-treated than control tumors.Fibrin deposition, as identified by Masson's Trichrome staining, wasincreased in and around blood vessels in the inner viable rim and thecentral necrotic core of soluble EphB4 treated than control tumors. Inthe outer viable rim of soluble EphB4 treated tumors, although thevessel lumen remained patent and contained red blood cells, fibrindeposition was evident around many vessels. Soluble EphB4 was found tohave no such effects on the endothelium in the normal tissues examined(lungs, liver and kidneys).

H. Materials and Methods

i) Expression Constructs

To construct expression vectors for producing soluble, 6×His-taggedEphB4-ECD variants, cloned full-length human EphB4 cDNA was amplified byPCR using the following oligo primers: TACTAGTCCGCCATGGAGCTCCGGGTGCTGCT(common EphB4 N-terminal primer) and GCGGCCGCTTAATGGTGATGGTGATGATGAGCCGAAGGA GGGGTGGTGCA (B4-GC), AGCGGCCGCTTAATGGTGATGGTGATGATGGACATTGA CAGGCTCAAATGGGA (B4-GCF1) or TGCGGCCGCTTAATGGTGATGGTGATGATGCTGCTCCCGCCAGCCCTCGCTCTCAT (B4-GCF2). The resulting PCR fragments wereTA-cloned into mammalian expression vector pEF6/V5-His-TOPO (Invitrogen)under EF-1α promoter control. The expressed recombinant proteins encodethe following fragments of the mature extracellular part of human EphB4:amino acid positions 1-522 (GCF2), 1-412 (GCF1) and 1-312 (GC). Togenerate the B4-CF2 deletion (δ amino acids 13-183) PCR fragment forpEF6 cloning, EphB4 cDNA was amplified by two-step overlap PCR usingoligo primers TACTAGTCCGCCATGGAGCTCCGGGTGCTGCT,CAGCTGAGTTTCCAATTTTGTGTTC, GAACACAAAATTGGAAACTCAGCTGACTGTGAACCTGAC andGCGGCCGCCCTG CTCCCGCCAGCCCTCGCT.

Vector for producing secreted human Ephr2-alkaline phosphatase (B2-AP)reagent was constructed by PCR amplification of human Ephrin B2 cDNAusing primers TAAAGCTTCCGCCATGGCTGTGAGAAGGGAC and TAGGATCCTTCGGAACCGAGGATGTTGTTCCC and cloning the resulting fragment, digested with HindIII and Bam HI, into Hind III-Bgl II digested pAPTag2 vector (GenHunter,Inc.). In each case, inserts in expression vectors were verified bycomplete sequencing.

2) Antibodies and Other Reagents

Anti-Eph B4 monoclonal antibodies mAB79 and nmAB23 were raised in miceagainst the GCF2 protein containing amino acids 1-522 of mature humanEphB4 and purified from hybridoma supernatants by Protein Achromatography. The anti-phosphotyrosine antibody 4G10 was from UBI(Lake Placid, N.Y.). Protein G-HRP conjugate was purchased from Bio-Rad.

3) Expression and Purification of EphB4-Derived Recombinant Proteins

To produce the EphB4-ECD soluble proteins, cultured human embryonickidney cells HEK293T were transfected with the corresponding plasmidconstructs using standard calcium phosphate or Lipofectam™ 2000 reagent(Invitrogen) protocols. Twelve to sixteen hours post-transfection, thegrowth medium (DMEM+10% fetal bovine serum) was aspirated, cells washedonce with serum free DMEM and replaced with serum free DMEM. Conditionedmedia containing the secreted proteins were harvested 72-96 hours later,clarified by centrifugation and used for purification of His-taggedproteins using Ni—NTA Agarose (Qiagen). The purity and quantity of therecombinant proteins was tested by SDS-PAAG electrophoresis withCoomassie Blue or silver staining, Western blotting and UV spectroscopy.Purified proteins were dialyzed against 20 mM Tris-HCl, 0.15 M NaCl, pH8 and stored at −70° C.

To test ligand binding properties of the proteins, 10 μl ofNi—NTA-Agarose (Qiagen) were incubated in microcentrifuge tubes with10-500 ng sample of a B4-ECD protein diluted in 0.5 ml of binding bufferBB (20 mM Tris-HCl, 0.15 M NaCl, 0.1% bovine serum albumin, pH 8). Afterincubation for 30 min on shaking platform, Ni—NTA beads were washedtwice with 1.4 ml of BB, followed by addition of B2-AP fusion protein atconcentration of 50 nM. Binding was performed for 30 min on a shakingplatform. Tubes were centrifuged and washed once with 1.4 ml of BB.Amount of precipitated AP was measured colorimetrically at 420 run afterapplication of p-nitrophenyl phosphate (PNPP) and incubation for 5-30min.

4) Immunoprecipitation

All lysates were processed at 4° C. Cells were lysed in 1 ml of buffercontaining 20 mM Hepes at pH 7.4, 100 mM sodium chloride, 50 mM sodiumfluoride, 2 mM EDTA, 2 mM EGTA, 1 mM sodium orthovanadate, 1%(v/v)NP-40, 0.5% (w/v) sodium deoxycholate, 1 mM phenyl methylsulphonylfluoride (added freshly) and 100 U Trasylol. Lysates were scraped intoEppendorf tubes and 50 μl of boiled, formalin-fixed Staphylococcusaureus was added (Calbiochem, San Diego). After 30 min of mixing, thelysates were centrifuged for 5 min at 25,000 g in a minifuge and thesupernatants transferred to new tubes containing the appropriateantibody. Lysates were mixed with antibodies for 1 h, after which time50 μl of protein A-Sepharose beads were added and the contents of thetubes mixed for 1 h to collect the immunoprecipitates. Protein A beadswere collected by centriftigation at 25,000 g for 30 s. The supernatantswere discarded and the beads washed three times with 1 ml lysis bufferminus deoxycholate.

5) Cell-Based EphB4 Trosine Kinase Assay

The human prostate carcinoma cell line PC3 cells were maintained in RPMImedium with 10% dialyzed fetal calf serum and 1%penicillin/streptomycin/neomycin antibiotics mix. Cells were maintainedat 37° C. in a humidified atmosphere of 5% CO₂/95% air. Typically, cellswere grown in 60 mm dishes until confluency and were either treated withmouse Ephrin B2-Fc fusion at 1 μg/ml in RPMI for 10 min to activateEphB4 receptor or plain medium as a control. To study the effect ofdifferent derivatives of soluble EphB4 ECD proteins on EphB4 receptoractivation, three sets of cells were used. In the first set, cells weretreated with various proteins (5 proteins; GC, GCF1, GCF2, GCF2-F, CF2)at 5 μg/ml for 20 min. In the second set of cells, prior to application,proteins were premixed with ephrinB2-Fc at 1:5 (EphB4 protein: B2-Fc)molar ratio, incubated for 20 min and applied on cells for 10 min. Inthe third set of cells, cells were first treated with the proteins for20 min at 5 μg/ml, media was replaced with fresh media containing 1μg/ml of EphrinB2-Fc and incubated for another 10 min.

After the stimulation, cells were immediately harvested with proteinextraction buffer containing 20 mM Tris-HCl, pH 7.4, 150 mM NaCl, 1%(v/v) Triton X100, 1 mM EDTA, 1 mM PMSF, 1 mM Sodium vanadate. Proteinextracts were clarified by centrifugation at 14,000 rpm for 20 min at 4°C. Clarified protein samples were incubated overnight with protein A/Gcoupled agarose beads pre-coated with anti-EphB4 monoclonal antibodies.The IP complexes were washed twice with the same extraction buffercontaining 0.1% Triton X100. The immunoprecipitates proteins weresolubilized in 1× SDS-PAGE sample loading buffer and separated on 10%SDS-PAGE. For EphB4 receptor activation studies, electroblotted membranewas probed with anti-pTyr specific antibody 4G10 at 1:1000 dilutionfollowed by Protein G-HRP conjugate at 1:5000 dilutions.

6) Cell Culture

Normal HUVECs were obtained from Cambrex (BioWhittaker) and maintainedin EBM2 medium supplemented with 0.1 mg/ml endothelial growth supplement(crude extract from bovine brain), penicillin (50 U/ml), streptomycin(50 U/ml), 2 mmol/l glutamine and 0.1 mg/ml sodium heparin. Aliquots ofcells were preserved frozen between passages 1 and 3. For allexperiments, HIUVECs were used at passages 4 or below and collected froma confluent dish.

7) Endothelial Cell Tube Formation Assay

Matrigel (60 μl of 10 mg/ml; Collaborative Lab, Cat. No. 35423) wasplaced in each well of an ice-cold 96-well plate. The plate was allowedto sit at room temperature for 15 minutes then incubated at 37° C. for30 minutes to permit Matrigel to polymerize. In the mean time, humanumbilical vein endothelial cells were prepared in EGM-2 (Clonetic, Cat.No. CC3162) at a concentration of 2×10⁵ cells/ml. The test protein wasprepared at 2× the desired concentration (5 concentration levels) in thesame medium. Cells (500 μl) and 2× protein (500 μl) were mixed and 200μl of this suspension were placed in duplicate on the polymerizedMatrigel. After 24 h incubation, triplicate pictures were taken for eachconcentration using a Bioquant Image Analysis system. Protein additioneffect (IC₅₀) was assessed compared to untreated controls by measuringthe length of cords formed and number of junctions.

8) Cell Migration Assay

Chemotaxis of HUVECs to VEGF was assessed using a modified Boydenchamber, transwell membrane filter inserts in 24 well plates, 6.5 mmdiam, 8 μm pore size, 10 μm thick matrigel coated, polycarbonatemembranes (BD Biosciences). The cell suspensions of HLJVECs (2×10⁵cells/ml) in 200 μl of EBM were seeded in the upper chamber and thesoluble EphB4 protein were added simultaneously with stimulant (VEGF orbFGF) to the lower compartment of the chamber and their migration acrossa polycarbonate filter in response to 10-20 ng/ml of VEGF with orwithout 100 nM-1 μM test compound was investigated. After incubation for4-24 h at 37° C., the upper surface of the filter was scraped with swaband filters were fixed and stained with Diff Quick. Ten random fields at200× mag were counted and the results expressed as mean # per field.Negative unstimulated control values were subtracted from stimulatedcontrol and protein treated sample values and the data was plotted asmean migrated cell±S.D. IC₅₀ was calculated from the plotted data.

9) Growth Inhibition Assay

HUVEC (1.5×10³ cells) were plated in a 96-well plate in 100 μl of EBM-2(Clonetic, Cat. No. CC3162). After 24 hours (day 0), the testrecombinant protein (100 μl) is added to each well at 2× the desiredconcentration (5-7 concentration levels) in EBM-2 medium. On day 0, oneplate was stained with 0.5% crystal violet in 20% methanol for 10minutes, rinsed with water, and air-dried. The remaining plates wereincubated for 72 h at 37° C. After 72 h, plates were stained with 0.5%crystal violet in 20% methanol, rinsed with water and air-dried. Thestain was eluted with 1:1 solution of ethanol: 0.1M sodium citrate(including day 0 Plate), and absorbance measured at 540 nm with an ELISAreader (Dynatech Laboratories). Day 0 absorbance was subtracted from the72 h plates and data is plotted as percentage of control proliferation(vehicle treated cells). IC₅₀ value was calculated from the plotteddata.

10) Murine Matrigel Plug Angiogenesis Assay

In vivo angiogenesis was assayed in mice as growth of blood vessels fromsubcutaneous tissue into a Matrigel plug containing the test sample.Matrigel rapidly forms a solid gel at body temperature, trapping thefactors to allow slow release and prolonged exposure to surroundingtissues. Matrigel (8.13 mg/ml, 0.5 ml) in liquid form at 4° C. was mixedwith Endothelial Cell Growth Supplement (ECGS), test proteins plus ECGSor Matrigel plus vehicle alone (PBS containing 0.25% BSA). Matrigel (0.5ml) was injected into the abdominal subcutaneous tissue of female nu/numice (6 wks old) along the peritoneal mid line. There were 3 mice ineach group. The animals were cared for in accordance with institutionaland NIH guidelines. At day 6, mice were sacrificed and plugs wererecovered and processed for histology. Typically the overlying skin wasremoved, and gels were cut out by retaining the peritoneal lining forsupport, fixed in 10% buffered formalin in PBS and embedded in paraffin.Sections of 3 μm were cut and stained with H&E or Masson's trichromestain and examined under light microscope

11) Mouse Corneal Micropocket assay

Mouse corneal micropocket assay was performed according to that detailedby Kenyon et al., 1996. Briefly, hydron pellets(polyhydroxyethylmethacrylate [polyHEMA], Interferon Sciences, NewBrunswick, N.J., U.S.A.) containing either 90 ng of bFGF (R&D) or 180 ngof VEGF (R&D Systems, Minneapolis, Minn., U.S.A.) and 40 μg of sucrosealuminium sulfate (Sigma) were prepared. Using an operating microscope,a stromal linear keratotomy was made with a surgical blade (Bard-Parkerno. 15) parallel to the insertion of the lateral rectus muscle in ananesthetized animal. An intrastromal micropocket was dissected using amodified von Graefe knife (2″30 mm). A single pellet was implanted andadvanced toward the temporal corneal limbus (within 0±7±1±0 mm for bFGFpellets and 0±5 mm for VEGF pellets). The difference in pellet locationfor each growth factor was determined to be necessary given therelatively weaker angiogenic stimulation of VEGF in this model.Antibiotic ointment (erythromycin.) was then applied to the operated eyeto prevent infection and to decrease surface irregularities. Thesubsequent vascular response was measured extending from the limbalvasculature toward the pellet and the contiguous circumferential zone ofneovascularization Data and clinical photos presented here were obtainedon day 6 after pellet implantation, which was found to be the day ofmaximal angiogenic response.

12) In vitro Invasion Assay

“Matrigel” matrix-coated 9-mm cell culture inserts (pore size, 8 μm;Becton Dickinson, Franklin Lakes, N.J.) were set in a 24-well plate. TheHUVEC cells were seeded at a density of 5×10³ cells per well into theupper layer of the culture insert and cultured with serum-free EBM inthe presence of EphB4 ECD for 24 h. The control group was cultured inthe same media without EphB4. Then 0.5 ml of the human SCC15 cell line,conditioned medium was filled into the lower layer of the culture insertas a chemo-attractant. The cells were incubated for 24 h, then theremaining cells in the upper layer were swabbed with cotton andpenetrating cells in the lower layer were fixed with 5% glutaraldehydeand stained with Diff Quick. The total number of cells passing throughthe Matrigel matrix and each 8 μm pore of the culture insert was countedusing optical microscopy and designated as an invasion index (cellnumber/area).

13) SCC15 Tumor Growth in Mice

Subcutaneously inject logarithmically growing SCC15, head and necksquamous cell carcinoma cell line, at 5×10⁶ cell density; with orwithout EphB4 ECD in the presence or absence of human bFGF, into athymicBalb/c nude mice, along with Matrigel (BD Bioscience) synthetic basementmembrane (1:1 v/v), and examine tumors within 2 weeks. Tumor volumes inthe EphB4 ECD group, in the presence and absence of growth factor afterimplantation were three-fold smaller than those in the vehicle groups.There was no difference in body weight between the groups.Immunohistochermical examination of cross-sections of resected tumorsand TUNEL-positive apoptosis or necrosis, CD34 immunostaining, and BrdUproliferation rate will be performed, after deparaffinized, rehydrated,and quenched for endogenous peroxidase activity, and after 10 minpermeabilization with proteinase K. Quantitative assessment of vasculardensities will also be performed. Local intratumoral delivery or IVdelivery of EphB4 ECD will also be performed twice a week.

30 athymic nude mice, BALB/c (nu/nu), were each injected with 1×10⁶ B16melanoma cells with 0.1 ml PBS mixed with 0.1 ml matrigel or 1.5×10⁶SCC15 cells resuspended in 200 μl of DMEM serum-free medium and injectedsubcutaneously on day 0 on the right shoulder region of mice. Proteinswere injected intravenously or subcutaneously, around the tumorbeginning on day 1 at a loading dose of 4 μg/mg, with weekly injectionsof 2 ug/mg. (10 μg/g, 50 μg/kg/day), and at 2 weeks post-inoculation.Mice are sacrificed on Day 14. Control mice received PBS 50 μl each day.

14) Tumor Formation in Nude Mice

All animals were treated under protocols approved by the institutionalanimal care committees. Cancer cells (5×10⁶) were subcutaneouslyinoculated into the dorsal skin of nude mice. When the tumor had grownto a size of about 100 mm³ (usually it took 12 days), sEphB4 was eitherintraperitoneally or subcutaneously injected once/day, and tumorigenesiswas monitored for 2 weeks. Tumor volume was calculated according to theformula a²×b, where a and b are the smallest and largest diameters,respectively. A Student's t test was used to compare tumor volumes, withP<0.05 being considered significant.

15) Quantification of Microvessel Density

Tumors were fixed in 4% formaldehyde, embedded in paraffin, sectioned by5 μm, and stained with hematoxylineosin. Vessel density wassemi-quantitated using a computer-based image analyzer (five fields persection from three mice in each group).

EXAMPLE 3 EphB4 Is Upregulated and Imparts Growth Advantage in ProstateCancer

A. Expression of EphB4 in Prostate Cancer Cell Lines

We first examined the expression of EphB4 protein in a variety ofprostate cancer cell lines by Western blot. We found that prostatecancer cell lines show marked variation in the abundance of the 120 kDEphB4. The levels were relatively high in PC3 and even higher in PC3M, ametastatic clone of PC3, while normal prostate gland derived cell lines(MLC) showed low or no expression of EphB4 (FIG. 27A). We next checkedthe activation status of EphB4 in PC3 cells by phosphorylation study. Wefound that even under normal culture conditions, EphB4 is phosphorylatedthough it can be further induced by its ligand, ephrin B2 (FIG. 27B).

B. Expression of EphB4 in Clinical Prostate Cancer Samples

To determine whether EphB4 is expressed in clinical prostate samples,tumor tissues and adjacent normal tissue from prostate cancer surgicalspecimens were examined. The histological distribution of EphB4 in theprostate specimens was determined by immunohistochemistry. Clearly,EphB4 expression is confined to the neoplastic epithelium (FIG. 28, topleft), and is absent in stromal and normal prostate epithelium (FIG. 28,top right). In prostate tissue array, 24 of the 32 prostate cancersexamined were positive. We found EphB4 mRNA is expressed both in thenormal and tumor tissues of clinical samples by quantitative RT-PCR.However, tumor EphB4 mRNA levels were at least 3 times higher than inthe normal in this case (FIG. 28, lower right).

C. p53 and PTEN Inhibited the Expression of EphB4 in PC3 Cells

PC3 cells are known to lack PTEN expression (Davis, et al., 1994,Science. 266:816-819) and wild-type p53 function (Gale, et al., 1997,Cell Tissue Res. 290:227-241). We investigated whether the relativelyhigh expression of EphB4 is related to p53 and/or PTEN by re-introducingwild-type p53 and/or PTEN into PC3 cells. To compensate for thetransfection efficiency and the dilution effect, transfected cells weresorted for the cotransfected truncated CD4 marker. We found that theexpression of EphB4 in PC3 cells was reduced by the re-introduction ofeither wild-type p53 or PTEN. The co-transfection of p53 and PTEN didnot further inhibit the expression of EphB4 (FIG. 29A).

D. Retinoid X Receptor (RXR α) Regulates the Expression of EphB4

We previously found that RXRα0 was down-regulated in prostate cancercell lines (Zhong, et al., 2003, Cancer Biol Ther. 2:179-184) and herewe found EphB4 expression has the reverse expression pattern when welooked at “normal” prostate (MLC), prostate cancer (PC3), and metastaticprostate cancer (PC3M) (FIG. 27A), we considered whether RXRα regulatesthe expression of EphB4. To confirm the relationship, the expression ofEphB4 was compared between CVR22R and CWR22R-RXRα, which constitutivelyexpresses RXRα. We found a modest decrease in EphB4 expression in theRXRα overexpressing cell line, while FGF8 has no effect on EphB4expression. Consistent with initial results, EphB4 was not found in“normal” benign prostate hypertrophic cell line BPH-1 (FIG. 29B).

E. Growth Factor Signaling Pathway of EGFR and IGF-1R Regulates EphB4Expression

EGFR and IGF-1R have both been shown to have autocrine and paracrineaction on PC3 cell growth. Because we found that EphB4 expression ishigher in the more aggressive cell lines, we postulated that EphB4expression might correlate with these pro-survival growth factors. Wetested the relationship by independently blocking EGFR and IGF-1Rsignaling. EphB4 was down-regulated after blocking the EGFR signalingusing EGFR kinase inhibitor AG 1478 (FIG. 30A) or upon blockade of theIGF-1R signaling pathway using IGF-1R neutralizing antibody (FIG. 30B).

F. EphB4 siRNA and Antisense ODNs Inhibit PC3 Cell Viability

To define the significance of this EphB4 overexpression in our prostatecancer model, we concentrated our study on PC3 cells, which have arelatively high expression of EphB4. The two approaches to decreasingEphB4 expression were siRNA and AS-ODNs. A number of differentphosphorothioate-modified AS-ODNs complementary to different segments ofthe EphB4 coding region were tested for specificity and efficacy ofEphB4 inhibition. Using 293 cells transiently transfected withfull-length EphB4 expression vector AS-10 was found to be the mosteffective (FIG. 31B). A Similar approach was applied to the selection ofspecific siRNA. EphB4 siRNA 472 effectively knocks down EphB4 proteinexpression (FIG. 31A). Both siRNA 472 and antisense AS-10 ODN reducedthe viability of PC3 cells in a dose dependent manner (FIG. 31C, D).Unrelated siRNA or sense oligonucleotide had no effect on viability.

G. EphB4 siRNA and Antisense ODNs Inhibit the Mobility of PC3 Cells

PC3 cells can grow aggressively locally and can form lymph nodemetastases when injected orthotopically into mice. In an effort to studythe role of EphB4 on migration of PC3 cells in vitro, we performed awound-healing assay. When a wound was introduced into a monolayer of PC3cells, over the course of the next 20 hours cells progressively migratedinto the cleared area. However, when cells were transfected with siRNA472 and the wound was introduced, this migration was significantlyinhibited (FIG. 31E). Pretreatment of PC3 cells with 10 μM EphB4 AS-10for 12 hours generated the same effect (FIG. 31F). In addition,knock-down of EphB4 expression in PC3 cells with siRNA 472 severelyreduced the ability of these cells to invade Matrigel as assessed by adouble-chamber invasion assay (FIG. 31G), compared to the control siRNA.

H. EphB4 siRNA Induces Cell Cycle Arrest and Apoptosis in PC3 Cells

Since knock-down of EphB4 resulted in decreased cell viability (FIG.31C) we sought to determine whether this was due to effects on the cellcycle. In comparison to control siRNA transfected cells, siRNA 472resulted in an accumulation of cells in the sub G0 and S phase fractionscompared to cells treated with control siRNA. The sub G0 fractionincreased from 1% to 7.9%, and the S phase fraction from 14.9% to 20.8%in siRNA 472 treated cells compared to control siRNA treated cells (FIG.32A). Cell cycle arrest at sub G0 and G2 is indicative of apoptosis.Apoptosis as a result of EphB4 knock-down was confirmed by ELISA assay.A dose-dependent increase in apoptosis was observed when PC3 cells weretransfected with siRNA 472, but not with control siRNA (FIG. 32B). At100 nM there was 15 times more apoptosis in siRNA 472 transfected thancontrol siRNA transfected PC3 cells.

I. Materials and Methods

1) Reagents

Neutralizing IGF-1R antibody was from R&D Systems (Minneapolis Minn.).Anti-IGF-1R(β), -EGFR, -EphB4(C-16) were from Santa Cruz Biotech (SantaCruz, Calif.). β-actin monoclonal antibody was purchased from SigmaChemical Co. (St Louis, Mo.). Media and fetal bovine serum (FBS) werefrom Invitrogen (Carlsbad, Calif.). AG1478(4-(3′-Chloroanilino)-6,7-dimethoxy-quinazoline) was from Calbiochem(San Diego, Calif.).

2) Antisense oligodeoxynucleotides and EphB4 siRNAs

EphB4 specific antisense phosphorothioate-modified oligodeoxynucleotide(ODN) and sense ODN were synthesized and purified by Qiagen (AlamedaCalif.). The sequences are: Sense, 5′-TCC-TGC-AAG-GAG-ACC-TTC-AC-3′;AS1: 5′-GTG-CAG-GGA-TAG-CAG-GGC-CAT-3′; AS10:5′-ATG-GAG-GCC-TCG-CTC-AGA-AA-3′. siRNAs were synthesized at theUSC/Norris Comprehensive Cancer Center Microchemical Core laboratory.Sequences of EphB4 siRNAs are siRNA 4725′-GGU-GAA-UGU-CAA-GAC-GCU-GTU-3′ and siRNA 23035′-cuc-uuc-cga-ucc-cac-cua-cuu-3′. Negative control siRNA to scrambledGAPDH was from Ambion (Austin, Tex.)

3) Cell Lines and Culture

The prostate cancer cell lines, PC3, PC3M, DU145, ALVA31, LAPC-4, LNCaP,CWR22R and adult human normal prostate epithelial cell line MLC SV40,and BPH-1 were obtained and cultured as described previously (7). Stablecell line CWR22R-RXR, LNCaP-FGF8 were established and cultured asdescribed before (7, 33).

4) Generation of EphB4 Monoclonal Antibody

The extracellular domain (ECD) of EphB4 was cloned into pGEX-4T-1 togenerate GST-fused ECD (GST-ECD). EphB4ECD expressed as a GST fusionprotein in BL21 E. coli was purified by affinity chromatography and theGST domain was cleaved by thrombin. Monoclonal antibody was generatedand the sensitivity and specificity of the antibody was reconfirmed byWestern blot with whole cell lysate of 293 cells stably transfected withEphB4.

5) One-Step RT-PCR and Quantitative RT-PCR

Total RNA was extracted using RNA STAT-60 (Tel-Test, Inc. FriendswoodTex.) from prostate cancer specimens and adjacent normal specimens. Forquantitative RT-PCR first strand cDNA was synthesized from 5 μg of totalRNA using SuperScript III (Invitrogen, Carlsbad Calif.). QuantitativeRT-PCR was performed on the Stratagene MX3000P system (Stratagene, LaJolla Calif.) using SYBR Green I Brilliant Mastermix (Stragene)according to the manufacture's instructions. Optimized reactions forEphB4 and β-actin (used as the normalizer gene) were 150 nM each of theforward primer (β-actin, 5′-GGA-CCT-GAC-TGA-CTA-CCT-A-3′; EphB4,5′-AAG-GAG-ACC-TTC-ACC-GTC-TT-3′) and reverse primer (β-actin5′-TTG-AAG-GTA-GTT-TCG-TGG-AT-3′; EphB4,5′-TCG-AGT-CAG-GTT-CAC-AGT-CA-3′) with DNA denaturation/activation ofpolymerase at 95° C. for 10 min followed by 40 cycles of 95° C. for 30s, 60° C. for 1 min, 72° C. for 1 min. The specificity of thegene-specific amplification was confirmed by the presence of a singledissociation peak. All reactions were performed in triplicate with RTand no template negative controls.

6) Immunohistochemistry

OCT-embedded tissues were sectioned at 5 μm and fixed inphosphate-buffered 4% paraformaldehyde. Sections were washed for 3×5 minin PBS and endogenous peroxidase was blocked by incubation in 0.3% H₂O₂in PBS for 10 min atroom temperature. Sections were incubated with Eph4(C-16) antibody (1:50) for 1 h at room temperature followed by threewashes in PBS and incubation with donkey anti-goat secondary antibody(Santa Cruz Biotech.) for 1 h at room temperature. After three washes inPBS, peroxidase activity was localized by incubation in DAB substratesolution (Vector Laboratories, Inc. Burlingame CA) for 10 min at roomtemperature. Sections were counter stained with Hematoxylin for 20 s,dehydrated and mounted. Negative control for staining was substitutionof normal goat serum for primary antibody. Immunohistochermical stainingon prostate array (BioMeda, Foster City, Calif.) was done using goat ABCStaining System (Santa Cruz Biotech.) according to the manufacturer'sinstructions.

7) Western Blot

Whole cell lysates were prepared using Cell Lysis Buffer (GeneHunter,Basgvukke Tenn.) supplemented with protease inhibitor cocktail (Pierce,Rockford Ill.), unless otherwise noted. Total protein was determinedusing the DC reagent system (Bio-Rad, Hercules Calif.). Typically, 20 μgwhole cell lysate was run on 4-20% Tris-Glycine gradient gel. Thesamples were electro-transferred to PVDF membrane and the non-specificbinding was blocked in TBST buffer (0.5 mM Tris-HCl, 45 mM NaCl, 0.05%Tween-20, pH 7.4) containing 5% non-fat milk. Membranes were firstprobed with primary antibody overnight, stripped with Restore™ WesternBlot stripping buffer (Pierce, Rockford Ill.) and reprobed with β-actinto confirm equivalent loading and transfer of protein. Signal wasdetected using SuperSignal West Femto Maximum Sensitivity Substrate(Pierce).

8) Phosphorylation Analysis

Cells growing in 60 nm dishes were either serum starved (1% FBSsupplemented RPMI 1640, 24 hours) or cultured in normal conditions (10%FBS) and then treated with or without 1 μg/ml mouse ephrin B2/F_(c) for10 min to activate EphB4 receptor Cleared cell lysates were incubatedwith EphB4 monoclonal antibody overnight at 4° C. Antigen-antibodycomplex was immunoprecipitated by the addition of 100 μl of ProteinG-Sepharose in 20 mM sodium phosphate, pH 7.0 with incubation overnightat 4° C. Immunoprecipitates were analyzed by Western blot with pTyrspecific antibody (Upstate, clone 4G10) at 1:1000 dilution followed byincubation with protein G-HRP (Bio-Rad) at 1:5000 dilution. To monitorimmunoprecipitation efficiency, a duplicate membrane was probed withEphB4 specific monoclonal antibody.

9) Transient Transfection and Sorting of Transfected Cells

PC3 cells were cotransfected with pMACS 4.1 coding for CD4 and wild typep53 (pC53-SN3) or PTEN vector or both using Lipofectamine 2000(Invitrogen) according to the manufacturer's instructions. The molarratio of CD4 to p53 or PTEN or vector was 1:3 and total plasmid was 24μg for a 10 cm² dish of 90% confluent cells using 60 μl of Lipofectamine2000. 24 hours after transfection, a single cell suspension was made andsorted using truncated CD4 as a surface marker according to themanufacturer's protocol (Miltenyi Biotec, Germany). Sorted cells werelysed in 1×SDS sampling buffer and analyzed by Western blot.

10) Study of IGF and EGF Signaling Pathway on the Expression of EphB4

PC3 cells were seeded into 6-well plates and cultured until 80%confluent and treated with 2 μg/ml neutralizing IGF-1R monoclonalantibody, MAB391 (Hailey, et al., 2002, Mol Cancer Ther. 1: 1349-1353),or with 1 nM AG 1478, a strong EGFR inhibitor (Liu, et al., 1999, J CellSci. 112 (Pt 14):2409-2417) for 24 h. Crude cell lysates were analyzedby Western blot. Band density was quantified with the Bio-Rad QuantityOne System software.

11) Cell Viability Assay

PC3 cells were seeded on 48-well plates at a density of approximately1×10⁴ cells/well in a total volume of 200 ml. Media was changed afterthe cells were attached and the cells were treated with variousconcentrations (1-10 μM) of EphB4 antisense ODN or sense ODN as control.After three days media was changed and fresh ODNs added. Following afurther 48 h incubation, cell viability was assessed by MTT as describedpreviously (36). EphB4 siRNAs (10-100 nM) were introduced into 2×10⁴ PC3cells/well of a 48-well plate using 2 μl of Lipofectamine™ 2000according to the manufacturer's instructions. 4 h post-transfection thecells were returned to growth media (RPMI 1640 supplemented with 10%FBS). Viability was assayed by MTT 48 h following transfection.

12) Wound Healing Migration Assay

PC3 cells were seeded into 6-well plates and cultured until confluent.10 μM AS-10 or sense ODN as control were introduced to the wells asdescribed for the viability assay 12 hours before wounding the monolayerby scraping it with a sterile pipette tip. Medium was changed to RPMI1640 supplemented with 5% FBS and fresh ODNs. Confluent culturestransfected with 50 nM siRNA 472 or GAPDH negative control siRNA 12hours prior to wounding were also examined. The healing process wasexamined dynamically and recorded with a Nikon Coolpix 5000 digitalcamera with microscope adapter.

13) Invasion Assay

PC3 cells were transfected with siRNA 472 or control siRNA usingLipofectamine™ 2000 and 6 hours later 0.5×105 cells were transferredinto 8 μm Matrigel-precoated inserts (BD Bioscience, Palo Alto, Calif.).The inserts were placed in companion wells containing RPMI supplementedwith 5% FBS and 5 μg/ml fibronectin as a chemoattractant. Following 22 hincubation the inserts were removed and the noninvading cells on theupper surface were removed by with a cotton swab. The cells on the lowersurface of the membrane were fixed in 100% methanol for 15 min, airdried and stained with Giemsa stain for 2 min. The cells were counted infive individual high-powered fields for each membrane under a lightmicroscope. Assays were performed in triplicate for each treatmentgroup.

14) Cell Cycle Analysis

80% confluent cultures of PC3 cells in 6-well plates were transfectedwith siRNA472 (100 nM) using Lipofectamine™ 2000. 24 hours aftertransfection, cells were trypsinized, washed in PBS and incubated for 1h at 4° C. in 1 ml of hypotonic solution containing 50 μg/ml propidiumiodide, 0.1% sodium citrate, 0.1 Triton X-100 and 20 μg/ml Dnase-freeRnaseA. Cells were analyzed in linear mode at the USC Flow cytometryfacility. Results were expressed as percentages of elements detected inthe different phases of the cell cycle, namely Sub G0 peak (apoptosis),G0/G1 (no DNA synthesis), S (active DNA systhesis), G2 (premitosis) andM (mitosis).

15) Apoptosis ELISA

Apoptosis was studied using the Cell Death Detection ELISAplus Kit(Roche, Piscataway, N.J.) according to the manufacturer's instructions.Briefly, PC3 80% confluent cultures in 24-well plates were transfectedusing Lipofectamine™ 2000 with various concentrations (0-100 nM) ofsiRNA 472 or 100 nM control siRNA. 16 hours later, cells were detachedand 1×10⁴ cells were incubated in 200 μl lysis buffer. Nuclei werepelleted by centrifugation and 20 μl of supernatant containing the mono-or oligonucleosomes was taken for ELISA analysis. Briefly, thesupernatant was incubated with anti-histone-biotin and anti-DNA-POD instreptavidin-coated 96-well plate for 2 hours at room temperature. Thecolor was developed with ABST and absorbance at 405 nm was read in amicroplate reader (Molecular Devices, Sunnyvale, Calif.).

EXAMPLE 4 Expression of EPHB4 in Mesothelioma: a Candidate Target forTherapy

Malignant mesothelioma (MM) is a rare neoplasm that most often arisesfrom the pleural and peritoneal cavity serous surface. The pleuralcavity is by far the most frequent site affected (>90%), followed by theperitoneum (6-10%) (Carbone et al., 2002, Semin Oncol. 29:2-17). Thereis a strong association with asbestos exposure, about 80% of malignantmesothelioma cases occur in individuals who have ingested or inhaledasbestos. This tumor is particularly resistant to the current therapiesand, up to now, the prognosis of these patients is dramatically poor(Lee et al., 2000, Curr Opin Pulm Med. 6:267-74).

Several clinical problems regarding the diagnosis and treatment ofmalignant mesothelioma remain unsolved. Making a diagnosis ofmesothelioma from pleural or abdominal fluid is notoriously difficultand often requires a thoracoscopic or laproscopic or open biopsy andImmunohistochermical staining for certain markers such as meosthelinexpressed preferentially in this tumor. Until now, no intervention hasproven to be curative, despite aggressive chemotherapeutic regimens andprolonged radiotherapy. The median survival in most cases is only 12-18months after diagnosis.

In order to identify new diagnostic markers and targets to be used fornovel diagnostic and therapeutic approaches, we assessed the expressionof EPHB4 and its ligand Ephri2 in mesothelioma cell lines and clinicalsamples.

A. EPHB4 and EphrinB2 is Expressed in Mesothelioma Cell Lines

The expression of Ephrin B2 and EphB4 in malignant mesothelioma celllines was determined at the RNA and protein level by a variety ofmethods. RT-PCR showed that all of the four cell lines express EphrinB2and EPHB4 (FIG. 33A). Protein expression was determined by Western blotin these cell lines. Specific bands for EphB4 were seen at 120 kD. Inaddition, Ephrin B2 was detected in all cell lines tested as a 37 kDband on Western blot (FIG. 33B). No specific band for Ephrin B2 wasobserved in 293 human embryonic kidney cells, which were included as anegative control.

To confirm the presence of EphB4 transcription in mesothelioma cells, insitu hybridization was carried out on NCI H28 cell lines cultured onchamber slides. Specific signal for EphB4 was detected using antisenseprobe Ephrin B2 transcripts were also detected in the same cell line.Sense probes for both EphB4 and Ephrin B2 served as negative controlsand did not hybridize to the cells (FIG. 34). Expression of EphB4 andEphrin B2 proteins was confirmed in the cell lines by immunofluorescenceanalysis (FIG. 35). Three cell lines showed strong expression of EphB4,Whereas expression of Ephrin B2 was present in H28 and H2052, and weaklydetectable in H2373.

B. Evidence of Expression of EPHB4 and EphrinB2 in Clinical Samples

Tumor cells cultured from the pleural effusion of a patient diagnosedwith pleural malignant mesothelioma were isolated and showed positivestaining for both EphB4 and Ephrin B2 at passage 1 (FIG. 35, bottomrow). These results confirm co-expression of EphB4 and Ephrin B2 inmesothelioma cell lines. To determine whether these results seen intumor cell lines were a real reflection of expression in the diseasestate, tumor biopsy samples were subjected to immunohistochemistrystaining for EphB4 and Ephrin B2. Antibodies to both proteins revealedpositive stain in the tumor cells. Representative data is shown in FIG.36.

C. EPHB4 is Involved in the Cell Growth and Migration of Mesothelioma

The role of EphB4 in cell proliferation was tested using EPHB4 specificantisepses oligonucleotides and siRNA. The treatment of cultured H28with EPHB4 antisense reduced cell viability. One of the most activeinhibitor of EphB4 expression is EPHB4AS-10 (FIG. 37A). Transfection ofEPHB4 siRNA 472 generated the same effect (FIG. 37B).

MM is a locally advancing disease with frequent extension and growthinto adjacent vital structures such as the chest wall, heart, andesophagus. In an effort to study this process in vitro, we perform woundhealing assay using previously described techniques (3:36). When a woundwas introduced into sub confluent H28 cells, over the course of the next28 hours cells would progressively migrate into the area of the wound.However, when cells were pretreated with EPHB4AS-10 for 24 hours, andthe wound was introduced, this migration was virtually completelyprevented (FIG. 38A). The migration study with Boyden Chamber assay withEPHB4 siRNA showed that cell migration was greatly inhibited with theinhibition of EPHB4 expression (FIG. 38B).

D. Materials and Methods

1) Cell Lines and Reagents

NCI H28, NCI H2052, NCI H2373, MSTO 2111H mesothelioma cell lines and293 human embryonic kidney cells were obtained from the ATCC (Manassas,Va.). Cells were maintained in RPMI 1640 media supplemented with 10%heat-inactivated fetal bovine serum (FBS; Life Technologies,Gaithersburg, Md.) and antibiotics. Primary cells were obtained frompleural effusion of patients with mesothelioma. A large number of EPHB4phosphorothioate modified antisense oligonucleotides were synthesized.Similarly a number of EphB4 specific siRNAs were generated. Monoclonalantibody produced against EPHB4 was used for western blot. Polyclonalantibody against EphrinB2 and EPHB4 (C-16) (for immunohistochemistrystaining) was from Santa Cruz.

2) RT-PCR

Total RNA was reversed transcribed by use of random hexamers(Invitrogen). Primers for EphB4 and EphrinB2 were designed with Primer 3software. The sequences for all primers are as follows: EPHB4 forwardprimer and EPHB4 reverse primer (see, e.g., in Example 2); EphrinB2forward primer and EphrinB2 reverse primer (see, e.g., in Example 6);G3PDH forward primer, 5′-GGAGCCAAAAGGGTCATCAT-3′; G3PDH reverse primer,5′-GGCATTGCTGCAAAGAAAGAG-3′; Clonetics kit was used for PCR. PCRs wereperformed with the ABI PCR System 2700 (Applied Biosystem). The PCRconditions were 95° C. for 5 min, followed by 35 cycles of 95° C. for 30seconds, 60° C. for 30 seconds and 72° C. for 1 min.

3) Preparation of Digoxigenin-Labeled RNA Probes

Ephrin-B2 and EphB4 PCR products were cloned using the pGEM-T EasySystem (Promega, Madison Wis.) according to the mnanufacturer'sdescription. The primers and PCR products were5′-tccgtgtggaagtactgctg-3′ (forward), 5′-tctggtttggcacagttgag-3′(reverse), for ephrin-B2 that yielded a 296-bp product and5′-ctttggaagagaccctgctg-3′ (forward), 5′-agacggtgaaggtctccttg-3′, forEphB4 that yielded a 297-bp product. The authenticity and insertorientation were confirmed by DNA sequencing.

The pGEM-T Easy plasmids containing the PCR product of the humanephrin-B2 or EphB4 gene were linearized with Spe I or Nco I. Antisenseor sense digoxigenin (DIG)-labeled RNA probes were transcribed from T7or SP6 promoters by run-off transcription using a DIG RNA labeling kit(Roche, Indianapolis Ind.). RNA probes were quantitated by spot assay asdescribed in the DIG RNA labeling kit instructions.

4) In situ Hybridization

Cells were cultured in Labtech II 4-well chamber slides (Nalge NuncInternational, Naperville, Ill.). Cells were washed in PBS (37° C.),then fixed for 30 min at 25° C. in a solution of 4% (w/v) formaldehyde,5% (v/v) acetic acid, and 0.9% (w/v) NaCl. After fixation, slides wererinsed with PBS and stored in 70% ethanol at 4° C. until further use.Before in situ hybridization, cells were dehydrated, washed in 100%xylene to remove residual lipid and then rehydrated, finally in PBS.Cells were permeabilized by incubating at 37° C. with 0.1% (w/v) pepsinin 0.1 N HCl for 20 min and post-fixed in 1% formaldehyde for 10 min.Prehybridization was performed for 30 min at 37° C. in a solution of4×SSC containing 50% (v/v) deionized formamide. Slides were hybridizedovernight at 42° C. with 25 ng antisense or sense RNA probes in 40%deionized formamide, 10% dextran sulfate, 1× Denhardt's solution, 4×SSC,10 mM DTT, 1 mg/ml yeast t-RNA and lmg/ml denatured and sheared salmonsperm DNA in a total volume of 40 μl. Slides were then washed at 37° C.as follows: 2×15 min with 2×SSC, 2×15min with 1×SSC, 2×15 min with0.5×SSC and 2×30 min with 0.2×SSC. Hybridization signal was detectedusing alkaline-phosphatase-conjugated anti-DIG antibodies (Roche)according to the manufacturer's instructions. Color development wasstopped by two washes in 0.1 M Tris-HCl, 1 mM EDTA, pH 8.0 for 10 min.Cells were visualized by counterstaining of nucleic acids with NuclearFast Red (Vector Laboratories, Burlingame, Calif.) and the slides weremounted with IMMU-MOUNT (Shandon, Astmoor UK).

5) Western Blot

Crude cell lysates were prepared by incubation in cell lysis buffer (10mM Tris, pH 7.5, 1 mM EDTA, 150 mM NaCl, 1% Triton X-100, 1 mM DTT, 10%glycerol). Lysates were cleared by centrifugation at 10,000×g for 10min. Total protein was determined by Bradford assay (Bio-Rad). Samples(20 μg protein) were fractionated on a 4-20% Tris-glycine polyacrylamidegel and transferred to polyvinylidene difluoride (PVDT) membrane(Bio-Rad) by electroblotting. Membranes were blocked with 5% non-fatmilk prior to incubation with antibody to EphB4 (1:5000 dilution) at 4°C., for 16 h. Secondary antibody (1:100,000 dilution) conjugated withhorseradish peroxidase was applied for 1 h at 25° C. The membranes weredeveloped using the SuperSignal West Femto Maximum sensitivitychemiluminescent substrate (Pierce, Rockford, Ill.) according to themanufacturer's instructions.

6) Immunohistochemistry

Formalin-fixed tissue sections were deparaffinized and incubated with10% goat serum at −70° C. for 10 minutes and incubated with the primaryrabbit antibodies against either Ephrin B2 or EphB4 (Santa CruzBiotechnologies; 1:100) at 4° C. overnight. Isotype-specific rabbit IgGwas used as control. The immunoreactivity for these receptors wasrevealed using an avidin-biotin kit from Vector Laboratories. Peroxidaseactivity was revealed by the diaminobenzidine (Sigma) cytochemicalreaction. The slides were then counter stained with H&E.

7) Immunofluorescence Studies

Cells were cultured on Labtech II 4-well chamber slides and fixed in 4%paraformaldehyde in Dulbecco's phosphate buffered saline pH 7.4 (PBS)for 30 min. The slides were rinsed twice in PBS and preincubated withblocking buffer (0.2% Triton-X100, 1% BSA in PBS) for 20 min. The slideswere then incubated with antibodies to EphB4 or ephrin B2 (1:100dilution in PBS) in blocking buffer at 4° C. for 16 hr. After washingthree times, the slides were incubated with the appropriatefluorescein-conjugated secondary antibodies (Sigma-Aldrich, St. Louis,Mo.). Nuclei were counter stained with 4′,6-diamidino-2-phenylindoledihydrochloride hydrate (DAPI), washed extensively with PBS and mountedwith Vectasheild antifade mounting solution (Vector Laboratories).Images were obtained using an Olympus AX70 fluorescence microscope andSpot v2.2.2 (Diagnostic Instruments Inc., Sterling Heights, Mich.)digital imaging system.

8) Cell Viability Assay

Cells were seeded at a density of 5×10³ per well in 48-well plates onday 0 in appropriate growth media containing 2% fetal calf serum (FCS).On the following day, the media was changed and cells were treated withvarious concentrations (1-10 μM) of EphB4 Antisense. On day 4, viabilitywas assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) at a final concentration of 0.5 mg/ml. Cells wereincubated for 2 hr, medium was aspirated, and: the cells were dissolvedin acidic isopropanol (90% isopropanol, 0.5% SDS and 40 mM HCl). Opticaldensity was read in an ELISA reader at 490 nm using isopropanol as blank(Molecular Devices, Calif.).

9) Cell Migration

In vitro wound healing assay was adopted. Briefly, cells were seededonto 6-cm plates in full culture media for 24 hours, and then switchedto medium containing 5% FBS. EPHB4 antisense 10 (10 μM) was also addedto treated well. 24 hours later, wounds were made using the tip of ap-200 pipette man; a line was drawn through the middle of the plates.The plate was photographed at 0, 12, 24 hours. The experiment wasrepeated three times.

EXAMPLE 5 EphB4 Is Expressed in Squamous Cell Carcinoma of The Head andNeck: Regulation by Epidermal Growth Factor Signaling Pathway and GrowthAdvantage

Squamous cell carcinoma of the head and neck (HNSCC) is the sixth mostfrequent cancer worldwide, with estimated 900,000 cases diagnosed eachyear. It comprises almost 50% of all malignancies in some developingnations. In the United States, 50,000 new cases and 8,000 deaths arereported each year. Tobacco carcinogens are believed to be the primaryetiologic agents of the disease, with alcohol consumption, age, gender,and ethnic background as contributing factors.

The differences between normal epithelium of the upper aerodigestivetract and cancer cells arising from that tissue are the result ofmutations in specific genes and alteration of their expression. Thesegenes control DNA repair, proliferation, immortalization, apoptosis,invasion, and angiogenesis. For head and neck cancer, alterations ofthree signaling pathways occur with sufficient frequency and producesuch dramatic phenotypic changes as to be considered the criticaltransforming events of the disease. These changes include mutation ofthe p53 tumor suppressor, overexpression of epidermal growth factorreceptor (EGFR), and inactivation of the cyclin dependent kinaseinhibitor p16. Other changes such as Rb mutation, ras activation, cyclinD amplification, and myc overexpression are less frequent in HNSCC.

Although high expression of EphB4 has been reported in hematologicmalignancies, breast carcinoma, endometrial carcinoma, and coloncarcinoma, there is limited data on the protein levels of EphB4, andcomplete lack of data on the biological significance of this protein intumor biology such as HNSCC.

A. HNSCC Tumors Express EphB4

We studied the expression of EphB4 in human tumor tissues byimmunohistochemistry, in situ hybridization, and Western blot. Twentyprospectively collected tumor tissues following IRB approval have beenevaluated with specific EphB4 monoclonal antibody that does not reactwith other members of the EphB and EphA family. EphB4 expression isobserved in all cases, with varying intensity of staining. FIG. 39A (topleft) illustrates a representative case, showing that EphB4 is expressedin the tumor regions only, as revealed by the H&E tumor architecture(FIG. 39A bottom left). Note the absence of staining for EphB4 in thestroma. Secondly, a metastatic tumor site in the lymph node showspositive staining while the remainder of the lymph node is negative(FIG. 39A, top right).

In situ hybridization was carried out to determine the presence andlocation of EphB4 transcripts in the tumor tissue. Strong signal forEphB4 specific antisense probe was detected indicating the presence oftranscripts (FIG. 39B, top left). Comparison with the H&E stain (FIG.39B, bottom left) to illustrate tumor architecture reveals that thesignal was localized to the tumor cells, and was absent from the stromalareas. Ephrin B2 transcripts were also detected in tumor sample, and aswith EphB4, the signal was localized to the tumor cells (FIG. 39B, topright). Neither EphB4 nor ephrin B2 sense probes hybridized to thesections, proving specificity of the signals.

B. High Expression of EphB4 in Primary and Metastatic Sites of HNSCC

Western blots of tissue from primary tumor, lymph node metastases anduninvolved tissue were carried out to determine the relative levels ofEphB4 expression in these sites. Tumor and normal adjacent tissues werecollected on 20 cases, while lymph nodes positive for tumor wereharvested in 9 of these 20 cases. Representative cases are shown in FIG.39C. EphB4 expression is observed in each of the tumor samples.Similarly, all tumor positive lymph nodes show EphB4 expression that wasequal to or greater than the primary tumor. No or minimal expression isobserved in the normal adjacent tissue.

C. EpeCB4 Expression and Regulation by EGFR Activity in HNSCC Cell Lines

Having demonstrated the expression of EphB4 limited to tumor cells, wenext sought to determine whether there was an in vitro model of EphB4expression in HNSCC. Six HN SCC cell lines were surveyed for EphB4protein expression by Western Blot (FIG. 40A). A majority of theseshowed strong EphB4 expression and thus established the basis forsubsequent studies. Since EGFR is strongly implicated in HNSCC we askedwhether EphB4 expression is associated with the activation of EGFR.Pilot experiments in SCC-15, which is an EGFR positive cell line,established an optimal time of 24 h and concentration of 1 mM of thespecific EGFR kinase inhibitor AG 1478 (FIG. 40B) to inhibit expressionof EphB4. When all the cell lines were studied, we noted robust EGFRexpression in all but SCC-4, where it is detectable but not strong (FIG.40C, top row). In response to EGFR inhibitor AG1478 marked loss in thetotal amount of EphB4 was observed in certain cell lines (SCC-15, andSCC-25) while no effect was observed in others (SCC-9,-12,-13 and -71).Thus SCC-15 and -25 serve as models for EpioB4 being regulated by EGFRactivity, while SCC-9,-12,-13 and -71 are models for regulation of EphB4in HNSCC independent of EGFR activity, where there may be input fromother factors such as p53, PTEN, IL-6 etc. We also noted expression ofthe ligand of EphB4, namely ephrin B2, in all of the cell lines tested.As with EphB4 in some lines ephrin B2 expression appears regulated byEGFR activity, while it is independent in other cell lines.

Clearly, inhibition of constitutive EGFR signaling repressed EphB4levels in SCC15 cells. We next studied whether EGF could induce EphB4.We found that EphB4 levels were induced in SCC15 cells that had beenserum starved for 24 h prior to 24 h treatment with 10 ng/ml EGF asshown in FIG. 41B (lanes 1 and 2). The downstream signaling pathwaysknown for EGFR activation shown in FIG. 41A, (for review see Yarden &Slikowski 2001) were then investigated for their input into EGF mediatedinduction of EphB4. Blocking PLCg, AKT and JNK phosphorylation with thespecific kinase inhibitors U73122, SH-5 and SP600125 respectivelyreduced basal levels and blocked EGF stimulated induction of EphB4 (FIG.41B, lanes 3-8). In contrast, inhibition of ERK1/2 with PD098095 andPI3-K with LY294002 or Wortmannin had no discernible effect on EGFinduction of EphB4 levels. However, basal levels of EphB4 were reducedwhen ERK1/2 phosphorylation was inhibited. Interestingly, inhibition ofp38 MAPK activation with SB203580 increased basal, but not EGF inducedEphB4 levels. Similar results were seen in the SCC25 cell line (data notshown).

D. Inhibition of EphB4 in High Expressing Cell Lines Results in ReducedViability and Causes Cell-Cycle Arrest

We next turned to the role of EphB4 expression in HNSCC by investigatingthe effect of ablating expression using siRNA or AS-ODN methods. SeveralsiRNAs to EphB4 sequence were developed (Table 1) which knocked-downEphB4 expression to varying degrees as seen in FIG. 42A. Viability wasreduced in SCC-15,-25 and -71 cell lines transfected with siRNAs 50 and472, which were most effective in blocking EphB4 expression (FIG. 42B).Little effect on viability was seen with EphB4 siRNA 1562 and 2302 orephrin B2 siRNA 254. Note that in SCC-4, which does not express EphB4(see FIG. 40A) there was no reduction in cell viability. The decreasedcell viability seen with siRNA 50 and 472 treatment was attributable toaccumulation of cells in sub G0, indicative of apoptosis. This effectwas both time and dose-dependant (FIG. 42C and Table 2). In contrast,siRNA2302 that was not effective in reducing EphB4 levels and had onlyminor effects on viability did not produce any changes in the cell cyclewhen compared with the mock Lipofectamine™ 2000 transfection. TABLE 1EphB4 siRNAs Name siRNA sequence Eph B4 50: 5′-GAGACCCUGCUGAACACAAUU-3′3′-UUCUCUGGGACGACUUGUGUU-5′ Eph B4 472: 5′-GGUGAAUGUCAAGACGCUGUU-3′3′-UUCCACUUACAGUUCUGCGAC-5′ Eph B4 1562: 5′-CAUCACAGCCAGACCCAACUU-3′3′-UUGUAGUGUCGGUCUGGGUUG-5′ Eph B4 2302 5′-CUCUUCCGAUCCCACCUACUU-3′3′-UUGAGAAGGCUAGGGUGGAUG-5′

TABLE 2 Effect of different EphB4 siRNA on Cell Cycle Treatment Sub G0G1 S G2 36 hr Lipo alone 1.9 39.7 21.3 31.8 100 nM 2302 2.0 39.3 21.231.2 100 nM 50 18.1 31.7 19.7 24.4 100 nM 472 80.2 10.9 5.2 2.1 16 hrLipo alone 7.8 55.7 15.2 18.5 100 nM 2302 8.4 57.3 14.3 17.3 10 nM 5010.4 53.2 15.7 17.7 100 nM 50 27.7 31.3 18.1 19.6 10 nM 472 13.3 50.215.8 17.5 100 nM 472 30.7 31.9 16.4 18.0

In addition, over 50 phosphorothioate AS-ODNs complementary to the humanEphB4 coding sequences were synthesized and tested for their ability toinhibit EphB4 expression in 293 cells transiently transfected with fulllength EphB4 expression plasmid. FIG. 43A shows a representative sampleof the effect of some of these AS-ODNs on EphB4 expression. Note thatexpression is totally abrogated with AS-10, while AS-11 has only a minoreffect. The effect on cell viability in SCC15 cells was most marked withAS-ODNs that are most effective in inhibiting EphB4 expression as shownin FIG. 43B. The IC₅₀ for AS-10 was approximately 1 μM, while even 10 μMAS-11 was not sufficient to attain 50% reduction of viability. When theeffect that AS-10 had on the cell cycle was investigated, it was foundthat the sub G0 fraction increased from 1.9% to 10.5% compared tonon-treated cells, indicative of apoptosis (FIG. 43C).

E. EphB4 Regulates Cell Migration

We next wished to determine if EphB4 participates in the migration ofHNSCC. Involvement in migration may have implications for growth andmetastasis. Migration was assessed using the wound-healing/scrape assay.Confluent SCC15 and SCC25 cultures were wounded by a single scrape witha sterile plastic Pasteur pipette, which left a 3 mm band with clearlydefined borders. Migration of cells into the cleared area in thepresence of test compounds was evaluated and quantitated after 24, 48and 72 hr. Cell migration was markedly diminished in response to AS-10that block EphB4 expression while the inactive compounds, AS-1 andscrambled ODN had little to no effect as shown in FIG. 43D. Inhibitionof migration with AS-i 0 was also shown using the Boyden double chamberassay (FIG. 43E).

F. EphB4 AS-10 in vivo Anti-Tumor Activity

The effect of EphB4 AS-10, which reduces cell viability and motility,was determined in SCC15 tumor xenografts in Balb/C nude mice. Dailytreatment of mice with 20 mg/kg AS-10, sense ODN or equal volume of PBSby I.P. injection was started the day following tumor cell implantation.Growth of tumors in mice receiving AS-10 was significantly retardedcompared to mice receiving either sense ODN or PBS diluent alone (FIG.44). Non-specific effects attributable to ODN were not observed, asthere was no difference between the sense ODN treated and PBS treatedgroups.

G. Materials and Methods

1) Cell Lines and Reagents

HNSCC-4,-9, 12,-13,-15,-25, and -71 were obtained from and 293 humanembryonic kidney cells were obtained from the ATCC (Manassas, Va.).Cells were maintained in RPMI 1640 media supplemented with 10%heat-inactivated fetal bovine serum (FBS; Invitrogen, Carlsbad, Calif.)and antibiotics. EGFR, EphB4(C-16) polyclonal antibodies were from SantaCruz Biotech (Santa Cruz, Calif.). β-actin monoclonal antibody waspurchased from Sigma Chemical Co. (St Louis, Mo.). Ephrin B2 and EphB4polyclonal antibodies and their corresponding blocking peptides wereobtained from Santa Cruz Biotechnology (Santa Cruz, Calif.). AG 1478(4-(3′-Chloroanilino)-6,7-dimethoxy-quinazoline) was from Calbiochem(San Diego, Calif.). Kinase inhibitors SH-5 and SP 600125 were from A.G.Scientific (San Diego, Calif.), PD98095, U73122, SB203580, LY294002, andWortmannin were obtained from Sigma.

2) Preparation of Digoxigenin-Labeled RNA Probes

See above, e.g., Example 3.

3) In situ Hybridization

See above, e.g., Example 3.

4) Immunohistochemistry

Formalin-fixed tissue sections were deparaffinized and incubated with10% goat serum at −70° C. for 10 minutes and incubated with the EphB4monoclonal antibody 4° C. overnight. Isotype specific rabbit IgG wasused as control. The immunoreactivity for these receptors was revealedusing an avidin-biotin kit from Vector Laboratories. Peroxidase activitywas revealed by the diaminobenzidine (Sigma) cytochemical reaction. Theslides were then counter stained with 0.12% methylene blue or H&E. Forfrozen sections, OCT-embedded tissues were sectioned at 5 μm and fixedin phosphate-buffered 4% paraformaldehyde. Sections were washed for 3×5min in PBS and endogenous peroxidase was blocked by incubation in 0.3%H₂O₂ in PBS for 10 min atroom temperature. Sections were incubated withEph4 (C-16) antibody (1:50) for 1 h at room temperature followed bythree washes in PBS and incubation with donkey anti-goat secondaryantibody (Santa Cruz Biotech.) for 1 h at room temperature. After threewashes in PBS, peroxidase activity was localized by incubation in DABsubstrate solution (Vector Laboratories, Inc. Burlingame Calif.) for 10min at room temperature. Sections were counter stained with Hematoxylinfor 20 s, dehydrated and mounted. Negative control forstaining wassubstitution of normal goat serum for primary antibody.Immunohistochermical staining on prostate array (BioMeda, Foster City,Calif.) was done using goat ABC Staining System (Santa Cruz Biotech.)according to the manufacturer's instructions.

5) Western Blot

See above, e.g., Example 3.

6) Synthesis of EphB4 siRNA by in vitro Transcription

The Silencer™ siRNA construction kit (Ambion, Austin Tex.) was used tosynthesize siRNA to EphB4. Briefly, 21 bp target sequences containing 19bp downstream of 5′-AA dinucleotides were identified that showed nosignificant homology to other sequences in the GenBank database. Senseand antisense siRNA 29-mer DNA oligonucleotide templates weresynthesized at the USC Norris Microchemical Core Facility. Antisensetemplate corresponded to the target sequence followed by 8 bp addition(5′-CCTGTCTC-3′) at the 3′ end complementary to the T7 promoter primerprovided by the SilencerTM siRNA construction kit. Sense templatecomprised 5′-AA followed by the complement of the target 19 bp, then theT7 8 bp sequence as above.

In separate reactions, the two siRNA oligonucleotide templates werehybridized to a T7 promoter primer. The 3′ ends of the hybridizedoligonucleotides were extended by the Klenow fragment of DNA polyrneraseto create double-stranded siRNA transcription templates. The sense andantisense siRNA templates were transcribed by T7 RNA polymerase and theresulting RNA transcripts were hybridized to create dsRNA. The leadersequences were removed by digesting the dsRNA with a single-strandedspecific ribonuclease leaving the overhanging WU dinucleotides. The DNAtemplate was removed at the same time by treatment with RNase freedeoxyribonuclease. The resulting siRNA was purified by glass fiberfilter binding to remove excess nucleotides, short oligomers, proteins,and salts in the reaction. The end products (shown in Table 3) weredouble-stranded 21-mer siRNAs with 3′ terminal uridine that caneffectively reduce the expression of target mRNA when transfected intocells.

A number of phosphorothioate AS-ODNs were also synthesized (Operon,Valencia Calif.) to test for inhibition of EphB4 expression (Table 3).TABLE 3 EphB4 Antisense ODNs Name Position Sequence (5′ → 3′) Eph B4 (552-572) GTG CAG GGA TAG CAG GGC CAT AS-1 Eph B4  (952-972) AAG GAGGGG TGG TGC ACG GTG AS-2 Eph B4 (1007-1027) TTC CAG GTG CAG GGA GGA GCCAS-3 Eph B4 (1263-1285) GTG GTG ACA TTG ACA GGC TCA AS-4 Eph B4(1555-1575) TCT GGC TGT GAT GTT CCT GGC AS-5 Eph B4  (123-140) GCC GCTCAG TTC CTC CCA AS-6 Eph B4  (316-333) TGA AGG TCT CCT TGC AGG AS-7 EphB4  (408-428) CGC GGC CAC CGT GTC CAC CTT AS-8 Eph B4 (1929-1949) CTTCAG GGT CTT GAT TGC CAC AS-9 Eph B4 (1980-1999) ATG GAG GCC TCG CTC AGAAA AS-10 Eph b4 (2138-2158) CAT GCC CAC GAG CTG GAT GAC AS-11

7) Cell Viability Assay

Cells were seeded at a density of 5×10³ per well in 48-well plates onday 0 in appropriate growth media containing 2% fetal calf serum (FCS).Cells were treated with various concentrations (1-10 μg/ml) of ODNs ondays 2 and 4. On day 5, viability was assessed using3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) aspreviously described (Masood et al '03). For viability with siRNA, 2×10⁴cells/well of SCC-4, -15, -25 or -71 in a 48-well plate were transfectedwith siRNAs (10-100 nM) using 2 μl of Lipofectamine™ 2000 according tothe manufacturer's instructions. 4 h post-transfection the cells werereturned to growth media (RPMI 1640 supplemented with 10% FBS).Viability was assayed by MTT 48 h following transfection.

8) Cell Cycle Analysis

80% confluent cultures of SCC15 cells in 6-well plates were transfectedwith siRNA472 (100 nM) using Lipofectamine™ 2000. Either 16 or 36 hoursafter transfection, cells were trypsinized, washed in PBS and incubatedfor 1 h at 4° C. in 1 ml of hypotonic solution containing 50 μg/mlpropidium iodide, 0.1% sodium citrate, 0.1 Triton X-100 and 20 μg/mlDNase-free RNaseA. Cells were analyzed in linear mode at the USC Flowcytometry facility. Results were expressed as percentages of elementsdetected in the different phases of the cell cycle, namely Sub G0 peak(apoptosis), G0/G1 (no DNA synthesis), S (active DNA systhesis), G2(premitosis) and M (mitosis). For AS-ODN experiment the cells wereexposed to 5 μM ODN for 36 h prior to processing.

9) Wound Healing Migration Assay

SCC15 cells were seeded into 6-well plates and cultured until confluent.10 μM AS-1, AS-10, or sense ODN as control were introduced to the wellsas described for the viability assay 12 hours before wounding themonolayer by scraping it with a sterile pipette tip. Medium was changedto RPMI 1640 supplemented with 5% FBS and fresh ODNs. The healingprocess was examined dynamically and recorded with a Nikon Coolpix 5000digital camera with microscope adapter.

10) Boyden Chamber Assay of Migration

Cell migration assays were performed as previously described (MasoodANUP paper '99) except that 1 μM AS-10 or AS-6 were added to the upperchamber. EGF (20 ng/ml) was used as chemoattractant in the lowerchamber. Taxol at 10 ng/ml was used as a negative control.

11) In vivo Studies

SCC15 (5×10⁶ cells) were injected subcutaneously in the lower back of5-week old male Balb/C Nu⁺/nu⁺ athymic mice. Treatment consisted ofdaily intraperitoneal injection of ODN (20 mg/kg in a total volume of100 μl) or diluent (PBS) begun the day following tumor cell implantationand continued for two weeks. Tumor growth in mice was measured aspreviously described (Masood CCR '01). Mice were sacrificed at theconclusion of the study. All mice were maintained in accord with theUniversity of Southern California Animal Care and Use Committeeguidelines governing the care of laboratory mice.

EXAMPLE 6 Ephrin B2 Expression in Kaposi's Sarcoma Is Induced by HumanHerpesvirus Type 8: Phenotype Switch from Venous to Arterial Endothelium

Kaposi's Sarcoma (KS) manifests as a multifocal angioproliferativedisease, most commonly of the skin and mucus membranes, with subsequentspread to visceral organs (1) Hallmarks of the disease are angiogenesis,edema, infiltration of lymphomononuclear cells and growth ofspindle-shaped tumor cells. Pathologically, established lesions exhibitan extensive vascular network of slit-like spaces. The KS vascularnetwork is distinct from normal vessels in the lack of basementmembranes and the abnormal spindle shaped endothelial cell (tumor cell)lining these vessels. Defective vasculature results in an accumulationof the blood components including albumin, red and mononuclear cells inthe lesions (1). The KS tumor is endothelial in origin; the tumor cellsexpress many endothelial markers, including lectin binding sites forUlex europeausagglutinin-1 (UEA-1), CD34, EN-4, PAL-E (2) and theendothelial cell specific tyrosine kinase receptors, VEGFR-1 (Flt-1),VEGFR-2 (Flk-1/KDR), VEGFR-3 (Flt-4), Tie-1 and Tie-2 (3, RM & PSGunpublished data). KS cells co-express lymphatic endothelial cellrelated proteins including LYVE and podoplanin (4).

The herpesvirus HHV-8 is considered the etiologic agent for the disease.In 1994 sequences of this new herpes virus were identified in KS tumortissue (5), and subsequent molecular-epidemiology studies have shownthat nearly all KS tumors contain viral genome. Sero-epidemiologystudies show that HIV infected patients with KS have the highestprevalence of HHV-8 and secondly that those with HIV infection but no KShave increased risk of developement of KS over the ensuing years if theyare also seropositive for HHV-8 (6). Direct evidence for the role ofHHV-8 in KS is the transformation of bone marrow endothelial cells afterinfection with HHV-8 (7). A number of HHV-8 encoded genes couldcontribute to cellular transformation (reviewed in 8). However, the mostevidence has accumulated for the G-protein coupled receptor (vGPCR) inthis role (9).

We investigated whether KS tumor cells are derived from arterial orvenous endothelium. In addition, we investigated whether HHV-8 has aneffect on expression of arterial or venous markers in a model of KS. KStumor cells were found to express the ephrin B2 arterial marker.Further, ephrin B2 expression was induced by HHV-8 VGPCR in KS andendothelial cell lines. Ephrin B2 is a potential target for treatment ofKS because inhibition of ephrin B2 expression or signaling wasdetrimental to KS cell viability and function.

A. KS Tumors Express Ephrin B2, but not EphB4

The highly vascular nature of KS lesions and the probable endothelialcell origin of the tumor cells prompted investigation of expression ofEphB4 and ephrin B2 which are markers for venous and arterialendothelial cells, respectively. Ephrin B2, but not EphB4 transcriptswere detected in tumor cells of KS biopsies by in situ hybridization(FIG. 45A). Comparison of the positive signal with ephrin B2 antisenseprobe and tumor cells as shown by H&E staining shows that ephrin B2expression is limited to the areas of the biopsy that contain tumorcells. The lack of signal in KS with EphB4 antisense probe is not due toa defect in the probe, as it detected transcripts in squarnous cellcarcinoma, which we have shown expresses this protein (18). Additionalevidence for the expression of ephrin B2 in KS tumor tissue is affordedby the localization of EphB4/Fc signal to tumor cells, detected by FITCconjugated anti human Fc antibody. Because ephrin B2 is the only ligandfor EphB4 this reagent is specific for the expression of ephrin B2 (FIG.45B, left). An adjacent section treated only with the secondary reagentshows no specific signal. Two-color confocal microscopy demonstrated thepresence of the HHV-8 latency protein, LANA1 in the ephrin B2 positivecells (FIG. 45C, left), indicating that it is the tumor cells, not tumorvessels, which are expressing this arterial marker. Staining of tumorbiopsy with PECAM-1 antibody revealed the highly vascular nature of thistumor (FIG. 45C, right). A pilot study of the prevalence of this patternof ephrin B2 and EphB4 expression on KS biopsies was conducted by RT-PCRanalysis. All six samples were positive for ephrin B2, while only 2 wereweakly positive for EphB4 (data not shown).

B. Infection of Venous Endothelial Cells with HHV-8 Causes a PhenotypeSwitch to Arterial Markers

We next asked whether HHV-8, the presumed etiologic agent for KS, coulditself induce expression of ephrin B2 and repress EphB4 expression inendothelial cells. Co-culture of HUVEC and BC-1 lymphoma cells, whichare productively infected with HHV-8, results in effective infection ofthe endothelial cells (16). The attached monolayers of endothelial cellsremaining after extensive washing were examined for ephrin B2 and EphB4by RT-PCR and immunofluorescence. HWVEC express EphB4 venous markerstrongly at the RNA level, but not ephrin B2 (FIG. 46B). In contrast,HHV-8 infected cultures (HUVEC/BC-1 and HUVEC/BC-3) express ephrin B2,while EphB4 transcripts are almost absent.

Imunofluorescence analysis of cultures of HUVEC and HUVEC/HHV-8 forartery/vein markers and viral proteins was undertaken to determinewhether changes in protein expression mirrored that seen in the RNA. Inaddition, cellular localization of the proteins could be determined.Consistent with the RT-PCR data HUVEC are ephrin B2 negative and EphB4positive (ig. 46A(a & m)). As expected they do not express any HHV-8latency associated nuclear antigen (LANA1) (FIG. 46A(b, n)). Co-cultureof BC-1 cells, which are productively infected with HHV-8, resulted ininfection of HUVEC as shown by presence of viral proteins LANA1 andORF59 (FIG. 46A(f, r)). HHV-8 infected HUVEC now express ephrin B2 butnot EphB4 (FIG. 46A(e, q, u), respectively). Expression of ephrin B2 andLANA1 co-cluster as shown by yellow signal in the merged image (FIG.46A(h)). HHV-8 infected HUVEC positive for ephrin B2 and negative forEph B4 also express the arterial marker CD 148 (19) (FIG. 46A (j, v)).Expression of ephrin B2 and CD 148 co-cluster as shown by yellow signalin the merged image (FIG. 46A(l)). Uninfected HUVEC expressing Eph B4were negative for CD148 (not shown).

C. HHV-8 vGPCR Induces Ephrin B2 Expression

To test whether individual viral proteins could induce the expression ofephrin B2 seen with the whole virus KS-SLK cells were stably transfectedwith HHV-8 LANA, or LANAA440 or vGPCR. Western Blot of stable clonesrevealed a five-fold induction of ephrin B2 in KS-SLK transfected withvGPCR compared to SLK-LANA or SLK-LANAA440 (FIG. 47A). SLK transfectedwith vector alone (PCEFL) was used as a control. SLK-vGPCR and SLK-pCEFLcells were also examined for ephrin B2 and Eph B4 expression byimmunofluorescence in transiently transfected KS-SLK cells. FIG. 47Bshows higher expression of ephrin B2 in the SLK-vGPCR cells compared toSLK-pCEFL. No changes in Eph B4 were observed in SLK-vGPCR compared toSLK-pCEFL. This clearly demonstrates that SLK-vGPCR cells expressed highlevels of ephrin B2 compared to SLK-pCEFL cells. This suggests thatvGPCR of HHV-8 is directly involved in the induction of Ephrin B2 andthe arterial phenotype switch in KS. Since we had shown that HHV-8induced expression of ephrin B2 in HWEC, we next asked if this could bemediated by a transcriptional effect. Ephrin B2 5′-flankingDNA-luciferase reporter plasmids were constructed as described in theMaterials and Methods and transiently transfected into HUVECs. Ephrin B25′-flanking DNA sequences-2491/-11 have minimal activity in HUVEC cells(FIG. 47C). This is consistent with ephrin B2 being an arterial, notvenous marker. However, we have noted that HUVEC in culture do expresssome ephrin B2 at the RNA level. Cotransfection of HHV-8 vGPCR inducesephrin B2 transcription approximately 10-fold compared to the controlexpression vector pCEFL. Roughly equal induction was seen with ephrin B2sequences-2491/-11, -1242/-11, or -577/-11, which indicates thatelements between -577 and -11 are sufficient to mediate the response tovGPCR, although maximal activity is seen with the -1242/-11 luciferaseconstruct.

D. Expression of Ephrin B2 is Regulated by VEGF and VEGF-C

We next asked whether known KS growth factors could be involved in thevGPCR-mediated induction of ephrin B2 expression. SLK-vGPCR cells weretreated with neutralizing antibodies to oncostatin-M, IL-6, IL-8, VEGFor VEGF-C for 36 hr. FIG. 48A shows that neutralization of VEGFcompletely blocked expression of ephrin B2 in SLK-vGPCR cells. A lesser,but significant decrease in ephrin B2 was seen neutralization of VEGF-Cand IL-8. No appreciable effect was seen with neutralization ofoncostatin-M or IL-6. To verify that VEGF and VEGF-C are integral to theinduction of ephrin B2 expression we treated HUVEC with VEGF, VEGF-C orEGF. HUVECs were grown in EBM-2 media containing 5% FBS with twodifferent concentration of individual growth factor (10 ng, 100 ng/ml)for 48 h. Only VEGF-A or VEGF-C induced ephrin B2 expression in a dosedependent manner (FIG. 48B). In contrast, EGF had no effect onexpression of ephrin B2.

E. Ephrin B2 siRNA Inhibits the Expression of Ephrin B2 in KS

Three ephrin B2 siRNA were synthesized as described in the methodssection. KS-SLK cells were transfected with siRNA and 48 h later ephrinB2 expression was deterrnined by Western Blot. Ephrin B2 siRNAs 137 or254 inhibited about 70% of ephrin B2 expression compared to controlsiRNA such as siRNA Eph B4 50 or siRNA GFP. Ephrin B2 63 siRNA was lesseffective than the above two siRNA Ephrin B2 (FIG. 49A).

F. Ephrin B2 is Necessary for Full KS and EC Viability, Cord Formationand in vivo Angiogenesis Activities

The most effective ephrin B2 siRNA (254) was then used to determinewhether inhibiting expression of ephrin B2 has any effect on the growthof KS-SLK or HIVEC cells. The viability of KS-SLK cells was decreased bythe same siRNAs that inhibited ephrin B2 protein levels (FIG. 49B).KS-SLK express high levels of ephrin B2 and this result showsmaintenance of ephrin B2 expression is integral to cell viability inthis setting. HUlVECs do not express ephrin B2, except when stimulatedby VEGF as shown in FIG. 48B. Ephrin B2 siRNA 264 dramatically reducedgrowth of HUVECs cultured with VEGF as the sole growth factor. Incontrast, no significant effect was seen when HUVECs were cultured withIGF, EGF and bFGF. As a control, EphB4 siRNA 50 had no detrimentaleffect on HUVECs in either culture condition (FIG. 49C).In addition toinhibition of viability of KS and primary endothelial cells, EphB4-ECDinhibits cord formation in HUVEC and KS-SLK and in vivo angiogenesis inthe Matrigel™ plug assay (FIG. 50).

G. Methods and Materials

1) Cell Lines and Reagents

Human vascular endothelial cells (HUVEC) were from Clonetics (San Diego,Calif.) and were maintained in EGM-2 and EGM-2MV media respectively(Clonetics). T1 human fibroblast line was from Dr. Peter Jones, USC.BC-1 and BC-3 human pleural effusion lymphoma cell lines and monoclonalantibodies to LANA1 and ORF59 were the kind gift of Dr. Dharamn Ablashi(Advanced Biotechnologies Inc., Columbia, Md.). KS-SLK was isolated froma Classic Kaposi's sarcoma patient (15). Polyclonal antibodies to EphB4,ephrin B2, CD 148, PECAM-1 were obtained from Santa Cruz Biotechnology(Santa Cruz, Calif.). Mouse EphB4/Fc and monoclonal antibodies to humanvascular endothelial growth factor (VEGF), VEGF-C, interleukin-(IL)6,IL-8 and oncostatin-M were purchased from R & D Systems (Minneapolis,Minn.). Expression vectors pKSvGPCR-CEFL and pCEFL were the kind gift ofDr. Enrique Mesri (Cornell University, New York, N.Y.). Expressionvectors for HHV-8 latency associated nuclear antigen (LANA) were kindlyprovided by Dr Matthew Rettig, Veteran's Administration Greater LosAngeles Healthcare System.

2) Collection and Preparation of Human Tissue

Human cutaneous Kaposi's sarcoma biopsy material was obtained underlocal anesthesia with informed consent from patients at the LACIUSCMedical Center, using an IRB approved consent form. Biopsies wereprocessed for either total RNA, paraffin blocks or frozen tissue blocksin OCT. Total RNA was extracted by homogenization in guanidineisothiocyanate, (RNAzol: Tel-Test, Inc., Friendswoods, Tex.). cDNAs weresynthesized by reverse transcriptase using a random hexamer primer(Superscript II; Invitrogen, Carlsbad, Calif.).

3) Preparation of Digoxigenin-Labeled RNA Probes

Ephrin B2 and EphB4 PCR products from the primers shown in Table 4 forin situ hybridization were cloned using the pGEM-T Easy system (Promega,Madison Wis.) according to the manufacturer's description using. Theauthenticity and insert orientation were confirmed by DNA sequencing.The pGEM-T Easy plasmids containing the PCR product of the humanephrin-B2 or EphB4 gene were linearized with Spe I or Nco I. Antisenseor sense digoxigenin (DIG)-labeled RNA probes were transcribed from T7or SP6 promoters by run-off transcription using a DIG RNA labeling kit(Roche, Indianapolis Ind.). RNA probes were quantitated by spot assay asdescribed in the DIG RNA labeling kit instructions. TABLE 4 Primers forEphrin B2 and EphB4. Product Gene Primer sequence Size (bp) ISH ProbePrimers ephrin B2 5′-TCC GTG TGG AGT ACT GCT G-3′ 296 5′-TCT GGT TTG GCACAG TTG AG-3′ EphB4 5′-CTT TGG AAG AGA CCC TGC TG-3′ 297 5′-AGA CGG TGAAGG TCT CCT TG-3′ RT-PCR Primers ephrin B2 5′-AGA CAA GAG CCA TGA AGATC-3′ 200 5′-GGA TCC CAC TTC GGA CCC GAG-3′ EphB4 5′-TCA GGT CAC TGC ATTGAA CGG G-3′ 400 5′-AAC TCG CTC TCA TCC AGT T-3′ β-actin 5′-GTG GGG CGCCCC AGG CAC CA-3′ 546 5′-CTC CTT AAT GTC ACG CAC GAT TTC-3′

4) In situ Hybridization

See above, e.g., Example 3.

5) Co-culture of HUVEC and BC-1

HUVEC cells were grown to 50-70% confluence in EGM-2 on gelatin-coatedLabtech II 4-well chamber slides (Nalge Nunc International, Naperville,Ill.). Co-culture with BC-1 or BC-3 was essentially as described bySakurada and coworkers (16). Briefly, BC-1 or BC-3 cells were pretreatedwith TPA (20 ng/ml) to induce virus for 48 hrs and then added to theHUVEC culture at a ratio of 10:1 for cocultivation for two days. TheHUVECs were washed extensively with PBS to remove the attached BC-1 orBC-3 cells.

6) Preparation of cDNA and RT-PCR

The TITANIUM: One-Step RT-PCR kit (Clontech, Palo Alto, Calif.) was usedfor RT-PCR from 1×10⁵ cells. Primer pairs for amplification of EphB4,ephrin B2 and β-actin are shown in Table 4. Each PCR cycle consisted ofdenaturation at 94° C. for 30 s, primer annealing at 60° C. for 30 s andextension at 72° C. for 30 s. The samples were amplified for 30 cycles.PCR products were separated on 1.5% agarose gels and stained withethidium bromide.

7) Cell Viability Assay

KS-SLK cells were seeded at a density of 1×10⁴ per well in 48-wellplates on day 0 in appropriate growth media containing 2% fetal calfserum (FCS). On the following day, the media was changed and cells weretreated with 0, 10 or 100 nM siRNA. On day 3, viability was assessedusing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)as previously described (17).

8) Immunofluorescence Studies

Cells cultured on Labtech II 4-well chamber slides or frozen sections ofKS biopsy material were fixed in 4% paraformaldehyde in Dulbecco'sphosphate buffered saline pH 7.4 (PBS) for 30 min. The slides wererinsed twice in PBS and preincubated with blocking buffer (0.2%Triton-X100, 1% BSA in PBS) for 20 min, followed by incubation withantibodies to EphB4, ephrin B2, CD148, LANA1 or ORF59 (1:100 dilution inPBS) in blocking buffer at 4° C. for 16 hr. After washing three times,the slides were incubated with the appropriate fluorescein orrhodamine-conjugated secondary antibodies (Sigma-Aldrich, St. Louis,Mo.). Nuclei were counter stained with 4′,6-diamidino-2-phenylindoledihydrochloride hydrate (DAPI), washed extensively with PBS and mountedwith Vectasheild antifade mounting solution (Vector Laboratories,Burlingame, Calif.). Images were obtained using a Olympus AX70fluorescence microscope and Spot v2.2.2 (Diagnostic Instruments Inc.,Sterling Heights, Mich.) digital imaging system.

Immunofluorescence detection of EphrinB2 with EPHB4-Fc was done asfollows. Frozen sections fixed in 4% paraformaldehyde and blocked with20% FBS were incubated with 5 μg/ml EphB4/Fc (R&D Systems) for 1 h atRT. Sections were then incubated with 10 gg/ml rabbit anti-humanIgG-FITC in PBS (Jackson ImmunoResearch Laboratories West Grove, Pa.) atRT for 1 hour. Nuclei were counter stained with DAPI and sectionsmounted as above. Human Fc (Jackson ImmunoResearch) was used as thenegative control.

9) Western Blot

Crude cell lysates were prepared, quantitated, fractionated andtransferred to membranes as described previously (17). Membranes wereblocked with 5% non-fat milk prior to incubation with antibody to ephrinB2 (1:5000 dilution) at 4° C., for 16 h. Secondary antibody (1:100,000dilution) conjugated with horseradish peroxidase was applied for 1 h at25° C. The membranes were developed using the SuperSignal West FemtoMaximum sensitivity chemiluminescent substrate (Pierce, Rockford, Ill.)according to the manufacturer's instructions. Membranes were strippedusing RestoreTm Western Blot Stripping Buffer (Pierce) and reprobed withEphB4 or actin.

10) Cord Formation Assay

Matrigel™ Basement Membrane Matrix (BD Biosciences Discovery Labware,Bedford, Mass.) was mixed with growth medium (3:1) on ice and 0.5 mlliquid placed in 24-well plates. Incubation of plates at 37° C. for 15min caused Matrigel™ polymerization. HUVEC or KS-SLK in exponentialphase growth were treated with 2 or 8 μg/ml EphB4-ECD or PBS as controlfor 16 h prior to trypsinizing and plating on the Matrigel™. Culture onMatrigel™ was continued in the presence of recombinant fusion proteinsfor 6 h. Cultures were fixed in 4% paraformaldehyde for 30 min andevaluated by inverted phase-contrast photomicroscopy.

11) Synthesis of Ephrin B2 and EphB4 siRNA by in vitro Transcription

The Silencer™ siRNA construction kit (Ambion, Austin Tex.) was used tosynthesize siRNA to ephrin B2 and EphB4. Briefly, three 21 bp targetsequences comprising 19 bp downstream of a 5′-AA dinucleotide wereidentified in the ephrin B2 cDNA (Accession number NM-004093) thatshowed no significant homology to other sequences in the GenBankdatabase. Sense and antisense siRNA 29-mer DNA oligonucleotide templateswere synthesized at the USC Norris Microchemical Core Facility.Antisense template corresponded to the target sequence followed by 8 bpaddition (5′-CCTGTCTC-3′) at the 3′ end complementary to the T7 promoterprimer provided with the Silencer SiRNA Construction Kit. Sense templatecomprised 5′-AA followed by the complement of the target 19 bp, then theT7 8 bp sequence as above. In separate reactions, the two siRNAoligonucleotide templates were hybridized to a T7 promoter primer. The3′ ends of the hybridized oligonucleotides were extended by the Klenowfragment of DNA polymerase to create double-stranded siRNA transcriptiontemplates. The sense and antisense siRNA templates were transcribed byT7 RNA polymerase and the resulting RNA transcripts were hybridized tocreate dsRNA. The dsRNA consisted of 5′ terminal single-stranded leadersequences, a 19 nt target specific dsRNA, and 3′ terminal UUs. Theleader sequences were removed by digesting the dsRNA with asingle-stranded specific ribonuclease. The DNA template was removed atthe same time by treatment with RNAse free deoxyribonuclease.

The resulting siRNAs were purified by glass fiber filter binding toremove excess nucleotides, short oligomers, proteins, and salts in thereaction. End product double-stranded 21 mer siRNAs are shown in Table5. Similarly, an EphB4 and green fluorescence protein (GFP) siRNAs weresynthesized. TABLE 5 siRNAs of ephrin B2 and EphB4. ephrin B2 2645′-GCAGACAGAUGCACUAUUAUU-3′ 3′-UUCGUCUGUCUACGUGAUAAU-5′ ephrin B2 63:5′-CUGCGAUUUCCAAAUCGAUUU-3′ 3′-UUGACGCUAAAGGUUUAGCUA-5′ ephrin B2 137:5′-GGACUGGUACUAUACCCACUU-3′ 3′-UUCCUGACCAUGAUAUGGGUG-5′ Eph B4 50:5′-GAGACCCUGCUGAACACAAUU-3′ 3′-UUCUCUGGGACGACUUGUGUU-5′ GFP5′-CGCUGACCCUGAAGUUCAUUU-3′ 3′-UUGCGACUGGGACUUCAAGUU-5′

12) Transfection of Ephrin B2 or EphB4 siRNA

HUVEC were seeded on eight-well chamber slides coated with fibronectinand grown overnight in EGM-2 (Cambrex, Walkersville, Md.). 16 h latermedia was replaced either with EBM-2 supplemented with 5% fetal calfserum (FCS) and EGM-2 BulletKit supplements bFGF, HEGF and R³-IGF-I atthe concentrations provided by the manufacturer, or EBM-2 supplementedwith 5% FCS and 10 ng/ml rhVEGF (R&D Systems). After 2 h incubation at37° C., the cells were transfected using Lipofectamine 2000 (1 μg/ml;Invitrogen) and 10 nM specific siRNAs in Opti-MEM-1 serum-free medium(Invitrogen). Following transfection for 2 hr in Opti-MEM-1, mediasupplemented as above was replaced in the appropriate wells. After 48hrs, the cells were stained with crystal violet and immediatelyphotographed at 1OX magnification.

13) Construction of Ephrin B2 Reporter Plasmids

Human ephrin B2 5′-flanking DNA from -2491 to -11 with respect to thetranslation start site was amplified from BACPAC clone RP11-29716(BacPac Resources, Children's Hospital, Oakland, Calif.) using theAdvantage GC Genomic PCR kit (Clontech Palo Alto, Calif.) to overcomethe large tracts of CG-rich sequence in the target area. Primers weredesigned to contain MluI sites for cloning. Amplified product wasdigested with MluI, gel purified and ligated into the MluI site in themultiple cloning site of pGL3Basic (Promega, Madison, Wis.). Orientationof the resulting clones was confnmed by restriction digest analysis. Thecorrect clone was designated pEFNB2_(-2491/11) luc. Digestion of thisclone with either KpnI or SacI followed by recircularization yieldedpEFNB2_(-1242/11) luc and pEFNB2_(-577/11) luc, respectively. PlasmidDNAs used for transient transfections were purified using a Mega Prepkit (QLAGEN, Valencia, Calif.).

14) Transient Transfection

HuvEC cells (0.8×10⁴ cells/well in 24 well plates) maintained in EGM-2media were transiently co-transfected with 0.5 μg/well ephrin B2promoter-luciferase constructs together with 50 ng/well either pCEFL orpKSvGPCR-CEFL, using Superfect reagent (QIAGEN) according to themanufacturer's instructions. Cells were harvested 48 h post-transfectionand lysed with Luciferase cell lysis buffer (Promega). Luciferaseactivity was assayed using the Luciferase Assay System (Promega)according to the manufacturer's instructions. Luciferase was normalizedto protein, because pCEFL-vGPCR induced the expression ofβ-galactosidase from pCMV-Sport-βgal (Invitrogen).

15) Construction and Purification of EpbB4 Extra Cellular Domain (ECD)Protein

See above, e.g., Example 1.

EXAMPLE 7 Expression of EphB4 in Bladder Cancer: a Candidate Target forTherapy

FIG. 51 shows expression of EPHB4 in bladder cancer cell lines (A), andregulation of EPHB4 expression by EGFR signaling pathway (B).

FIG. 52 shows that transfection of p53 inhibit the expression of EPHB4in 5637 cell.

FIG. 53 shows growth inhibition of bladder cancer cell line (5637) upontreatment with EPHB4 siRNA 472.

FIG. 54 shows results on apoptosis study of 5637 cells transfected withEPHB4 siRNA 472.

FIG. 55 shows effects of EPHB4 antisense probes on cell migration. 5637cells were treated with EPHB4AS10 (10 μM).

FIG. 56 shows effects of EPHB4 siRNA on cell invasion. 5637 cells weretransfected with siRNA 472 or control siRNA.

EXAMPLE 8 Inhibition of EphB4 Gene Expression by EphB4 Antisense Probesand RNAi probes

Cell lines expressing EphB4 were treated with the syntheticphosphorothioate modified oligonucleotides and harvested after 24 hr.Cell lysates were prepared and probed by western blot analysis forrelative amounts of EphB4 compared to untreated control cells.

Studies on inhibition of cell proliferation were done in HNSCC celllines characterized to express EphB4. Loss of cell viability was shownupon knock-down of EphB4 expression. Cells were treated in vitro andcultured in 48-well plates, seeded with 10 thousand cells per well. Testcompounds were added and the cell viability was tested on day 3. Theresults on EphB4 antisense probes were summarized below in Table 6. Theresults on EphB4 RNAi probes were summarized below in Table 7. TABLE 6Inhibition of EphB4 Gene Expression by EphB4 antisense probes PercentInhibition reduction of EphB4 in Name Sequence 5′ → 3′ positionExpression viability Eph B4 169 TCA GTA CTG CGG GGC CGG TCC (2944-2963)++ 36 Eph B4 168 TCC TGT CCC ACC CGG GGT TC (2924-2943) ++ 51 Eph B4 167CCG GCT TGG CCT GGG ACT TC (2904-2923) +++ 66 Eph B4 166 ATG TGC TGG ACACTG GCC AA (2884-2903) ++++ 70 Eph B4 165 GAT TTT CTT CTG GTG TCC CG(2864-2883) ++++ 75 Eph B4 164 CCA GAG TGA CTC CGA TTC GG (2844-2863) ++40 Eph B4 163 AGC AGG TCC TCA GCA GAG AT (2824-2843) ++++ 66 Eph B4 162CTG GCT GAC CAG CTC GAA GG (2804-2823) 25 Eph B4 161 AGC CAA AGC CAG CGGCTG CG (2784-2803) + 33 Eph B4 160 AAA CTT TCT TCG TAT CTT CC(2763-2783) + 25 Eph B4 159 CAT TTT GAT GGC CCG AAG CC (2743-2762) ++ 40Eph B4 158 ACT CGC CCA CAG AGC CAA AA (2723-2742) 30 Eph B4 157 GCT GAGTAG TGA GGC TGC CG (2703-2722) + 25 Eph B4 156 CTG GTC CAG GAG AGG GTGTG (2683-2702) ++ 30 Eph B4 155 AGG CCC CGC CAT TCT CCC GG (2663-2682)25 Eph B4 154 GCC ACG ATT TTG AGG CTG GC (2643-2662) ++ 40 Eph B4 153GGG GTT CCG GAT CAT CTT GT (2623-2642) ++ 35 Eph B4 152 CCA GGG CGC TGACCA CCT GG (2603-2622) + 30 Eph B4 151 GGG AAG CGG GGC CGG GCA TT(2583-2602) + 25 Eph B4 150 CCG GTC TTT CTG CCA ACA GT (2563-2582) ++ 25Eph B4 149 CCA GCA TGA GCT GGT GGA GG (2543-2562) ++ 20 Eph B4 148 GAGGTG GGA CAG TCT GGG GG (2523-2542) + 30 Eph B4 147 CGG GGG CAG CCG GTAGTC CT (2503-2522) ++ 40 Eph B4 146 GTT CAA TGG CAT TGA TCA CG(2483-2502) ++++ 70 Eph B4 145 TCC TGA TTG CTC ATG TCC CA (2463-2482)++++ 80 Eph B4 144 GTA CGG CCT CTC CCC AAA TG (2443-2462) +++ 60 Eph B4143 ACA TCA CCT CCC ACA TCA CA (2423-2442) ++++ 80 Eph B4 142 ATC CCGTAA CTC CAG GCA TC (2403-2422) ++ 40 Eph B4 141 ACT GGC GGA AGT GAA CTTCC (2383-2402) +++ 50 Eph B4 140 GGA AGG CAA TGG CCT CCG GG (2363-2382)++ 45 Eph B4 139 GCA GTC CAT CGG ATG GGA AT (2343-2362) ++++ 70 Eph B4138 CTT TCC TCC CAG GGA GCT CG (2323-2342) ++++ 70 Eph B4 137 TGT AGGTGG GAT CGG AAG AG (2303-2322) ++ 40 Eph B4 136 TTC TCC TCC AGG AAT CGGGA (2283-2302) ++ 35 Eph B4 135 AAG GCC AAA GTC AGA CAC TT (2263-2282)++++ 60 Eph B4 134 GCA GAC GAG GTT GCT GTT GA (2243-2262) ++ 50 Eph B4133 CTA GGA TGT TGC GAG CAG CC (2223-2242) ++ 40 Eph B4 132 AGG TCT CGGTGG ACG TAG CT (2203-2222) ++ 40 Eph B4 131 CAT CTC GGC AAG GTA CCG CA(2183-2202) +++ 50 Eph B4 130 TGC CCG AGG CGA TGC CCC GC (2163-2182) ++50 Eph B4 129 AGC ATG CCC ACG AGC TGG AT (2143-2162) ++ 50 Eph B4 128GAC TGT GAA CTG TCC GTC GT (2123-2142) ++ 50 Eph B4 127 TTA GCC GCA GGAAGG AGT CC (2103-2122) +++ 60 Eph B4 126 AGG GCG CCG TTC TCC ATG AA(2083-2102) ++ 50 Eph B4 125 CTC TGT GAG AAT CAT GAC GG (2063-2082) ++++80 Eph B4 124 GCA TGC TGT TGG TGA CCA CG (2043-2062) ++++ 70 Eph B4 123CCC TCC AGG CGG ATG ATA TT (2023-2042) ++ 50 Eph B4 122 GGG GTG CTC GAACTG GCC CA (2003-2022) ++++ 80 Eph B4 121 TGA TGG AGG CCT CGC TCA GA(1983-2002) ++ 50 Eph B4 120 AAC TCA CGC CCC TGC CCC TC (1963-1982) ++40 Eph B4 119 CGT GTA GCC ACC CTT CAG GG (1943-1962) ++++ 75 Eph B4 118TCT TGA TTG CCA CAC AGC TC (1923-1942) ++++ 80 Eph B4 117 TCC TTC TTCCCT GGG GCC TT (1903-1922) ++++ 70 Eph B4 116 GAG CCG CCC CCG GCA CAC CT(1883-1902) ++ 50 Eph B4 115 CGC CAA ACT CAC CTG CAC CA (1863-1882) ++++60 Eph B4 114 ATC ACC TCT TCA ATC TTG AC (1843-1862) ++++ 65 Eph B4 113GTA GGA GAC ATC GAT CTC TT (1823-1842) ++++ 90 Eph B4 112 TTG CAA ATTCCC TCA CAG CC (1803-1822) ++++ 70 Eph B4 111 TCA TTA GGG TCT TCA TAA GT(1783-1802) ++++ 70 Eph B4 110 GAA GGG GTC GAT GTA GAC CT (1763-1782)++++ 80 Eph B4 109 TAG TAC CAT GTC CGA TGA GA (1743-1762) ++ 50 Eph B4108 TAC TGT CCG TGT TTG TCC GA (1723-1742) ++ 45 Eph B4 107 ATA TTC TGCTTC TCT CCC AT (1703-1722) ++++ 70 Eph B4 106 TGC TCT GCT TCC TGA GGC AG(1683-1702) ++++ 70 Eph B4 105 AGA ACT GCG ACC ACA ATG AC (1663-1682) ++40 Eph B4 104 CAC CAG GAC CAG GAC CAC AC (1643-1662) ++++ 70 Eph B4 103CCA CGA CTG CCG TGC CCG CA (1623-1642) ++ 40 Eph B4 102 ATC AGG CCC AGCTGC TCC CG (1603-1622) +++ 50 Eph B4 101 CCA GCC CTC GCT CTC ATC CA(1583-1602) ++++ 80 Eph B4 100 GTT GGG TCT GGC TGT GAT GT (1563-1582)++++ 80 Eph B4 99 TCC TGG CCG AAG GGC CCG TA (1543-1562) ++ 35 Eph B4 98GCC GGC CTC AGA GCG CGC CC (1523-1542) ++ 50 Eph B4 97 GTA CCT GCA CCAGGT AGC TG (1503-1522) ++++ 80 Eph B4 96 GCT CCC CGC TTC AGC CCC CG(1483-1502) ++ 50 Eph B4 95 CAG CTC TGC CCC GTT TTC TG (1463-1482) ++ 50Eph B4 94 ACG TCT TCA GGA ACC GCA CG (1443-1462) ++++ 80 Eph B4 93 CTGCTG GGA CCC TCG GCG CC (1423-1442) ++ 40 Eph B4 92 CTT CTC ATG GTA TTTGAC CT (1403-1422) ++++ 80 Eph B4 91 CGT AGT CCA GCA CAG CCC CA(1383-1402) ++++ 85 Eph B4 90 CTG GGT GCC CGG GGA ACA GC (1363-1382) +++50 Eph B4 89 CCA GGC CAG GCT CAA GCT GC (1343-1462) ++++ 70 Eph B4 88TGG GTG AGG ACC GCG TCA CC (1323-1342) ++ 40 Eph B4 87 CGG ATG TCA GACACT GCA GG (1303-1322) ++++ 60 Eph B4 86 AGG TAC CTC TCG GTC AGT CC(1283-1302) ++ 50 Eph B4 85 TGA CAT TGA CAG GCT CAA AT (1263-1282) ++++80 Eph B4 84 GGG ACG GGC CCC GTG GCT AA (1243-1262) ++ 50 Eph B4 83 GGAGGA TAC CCC GTT CAA TG (1223-1242) +++ 60 Eph B4 82 CAG TGA CCT CAA AGGTAT AG (1203-1222) ++++ 70 Eph B4 81 GTG AAG TCA GGA CGT AGC CC(1183-1202) +++ 60 Eph B4 80 TCG AAC CAC CAC CCA CCC CT (1163-1182) +++50 Eph B4 79 CCA CCA GGT CCC GGG GGC CG (1143-1162) ++ 40 Eph B4 78 GGGTCA AAA GTC AGG TCT CC (1123-1142) ++++ 70 Eph B4 77 CCC GCA GGG CGC ACAGGA GC (1103-1122) +++ 60 Eph B4 76 CTC CGG GTC GGC ACT CCC GG(1083-1102) +++ 60 Eph B4 75 CAG CGG AGG GCG TAG GTG AG (1063-1082) ++40 Eph B4 74 GTC CTC TCG GCC ACC AGA CT (1043-1062) ++ 50 Eph B4 73 CCAGGG GGG CAC TCC ATT CC (1023-1042) ++ 50 Eph B4 72 AGG TGC AGG GAG GAGCCG TT (1003-1022) ++++ 70 Eph B4 71 CAG GCG GGA AAC CAC GCT CC (983-1002) ++ 40 Eph B4 70 GCG GAG CCG AAG GAG GGG TG  (963-982) +++ 50Eph B4 69 GTG CAG GGT GCA CCC CGG GG  (943-962) +++ 50 Eph B4 68 GTC TGTGCG TGC CCG GAA GT  (923-942) ++ 40 Eph B4 67 ACC CGA CGC GGC ACT GGC AG (903-922) ++ 40 Eph B4 66 ACG GCT GAT CCA ATG GTG TT  (883-902) ++ 50Eph B4 65 AGA GTG GCT ATT GGC TGG GC  (863-882) ++++ 60 Eph B4 64 ATGGCT GGC AGG ACC CTT CT  (843-862) ++++ 80 Eph B4 63 CCT GAC AGG GGC TTGAAG GT  (823-842) ++++ 80 Eph B4 62 GCC CTG GGC ACA GGC TCG GC (803-822) +++ 70 Eph B4 61 ACT TGG TGT TCC CCT CAG CT  (783-802) ++++80 Eph B4 60 GCC TCG AAC CCC GGA GCA CA  (763-782) +++ 50 Eph B4 59 GCTGCA GCC CGT GAC CGG CT  (743-762) +++ 50 Eph B4 58 GTT CGG CCC ACT GGCCAT CC  (723-742) ++ 45 Eph B4 57 TCA CGG CAG TAG AGG CTG GG  (703-722)+++ 70 Eph B4 56 GCT GGG GCC AGG GGC GGG GA  (683-702) ++ 50 Eph B4 55CGG CAT CCA CCA CGC AGC TA  (663-682) ++ 50 Eph B4 54 CCG GCC ACG GGCACA ACC AG  (643-662) ++ 50 Eph B4 53 CTC CCG AGG CAC AGT CTC CG (623-642) +++ 50 Eph B4 52 GGA ATC GAG TCA GGT TCA CA  (603-622) ++++90 Eph B4 51 GTC AGC TGG GCG CAC TTT TT  (583-602) +++ 70 Eph B4 50 GTAGAA GAG GTG CAG GGA TA  (563-582) ++++ 80 Eph B4 49 GCA GGG CCA TGC AGGCAC CC  (543-562) ++++ 80 Eph B4 48 TGG TCC TGG AAG GCC AGG TA (523-542) ++++ 90 Eph B4 47 GAA GCC AGC CTT GCT GAG CG  (503-522) ++++80 Eph B4 46 GTC CCA GAC GCA GCG TCT TG  (483-502) ++ 40 Eph B4 45 ACATTC ACC TTC CCG GTG GC  (463-482) +++ 50 Eph B4 44 CTC GGC CCC AGG GCGCTT CC  (443-462) ++ 50 Eph B4 43 GGG TGA GAT GCT CCG CGG CC  (423-442)+++ 60 Eph B4 42 ACC GTG TCC ACC TTG ATG TA  (403-422) ++++ 80 Eph B4 41GGG GTT CTC CAT CCA GGC TG  (383-402) ++++ 80 Eph B4 40 GCG TGA GGG CCGTGG CCG TG  (363-382) ++ 50 Eph B4 39 TCC GCA TCG CTC TCA TAG TA (343-362) +++ 60 Eph B4 38 GAA GAC GGT GAA GGT CTC CT  (323-342) ++++80 Eph B4 37 TGC AGG AGC GCC CAG CCC GA  (303-322) +++ 50 Eph B4 36 GGCAGG GAC AGG CAC TCG AG  (283-302) +++ 45 Eph B4 35 CAT GGT GAA GCG CAGCGT GG  (263-282) ++ 50 Eph B4 34 CGT ACA CGT GGA CGG CGC CC  (243-262)++ 40 Eph B4 33 CGC CGT GGG ACC CAA CCT GT  (223-242) +++ 60 Eph B4 32GCG AAG CCA GTG GGC CTG GC  (203-222) ++++ 70 Eph B4 31 CCG GOG CAC GCTGCA CGT CA  (183-202) +++ 60 Eph B4 30 CAC ACT TCG TAG GTG CGC AC (163-182) +++ 70 Eph B4 29 GCT GTG CTG TTC CTC ATC CA  (143-162) ++++80 Eph B4 28 GGC CGC TCA GTT CCT CCC AC  (123-142) ++ 40 Eph B4 27 TGCCCG TCC ACC TGA GGG AA  (103-122) ++ 50 Eph B4 26 TGT CAC CCA CTT CAGATC AG   (83-102) ++++ 70 Eph B4 25 CAG TTT CCA ATT TTG TGT TC   (63-82)++++ 70 Eph B4 24 AGC AGG GTC TCT TCC AAA GC   (43-62) ++++ 80 Eph B4 23TGC GGC CAA CGA AGC CCA GC   (23-42) ++ 50 Eph B4 22 AGA GCA GCA CCC GGAGCT CC    (3-22) +++ 50 Eph B4 21 AGC AGC ACC CGG AGC TCC AT    (1-20)+++ 50 Additional antisense probes described in the specification EphB4AS-1 GTG CAG GGA TAG CAG GGC CAT  (552-572) EphB4 AS-2 AAG GAG GGG TGGTGC ACG GTG  (952-972) EphB4 AS-3 TTC CAG GTG CAG GGA GGA GCC(1007-1027) EphB4 AS-4 GTG GTG ACA TTG ACA GGC TCA (1263-1285) EphB4AS-6 TCT GGC TGT GAT GTT CCT GGC (1555-1575) EphB4 AS-6 CCC GCT CAG TTCCTC CCA  (123-140) EphB4 AS-7 TGA AGG TCT CCT TOC AGG  (316-333) EphB4AS-8 CGC GGC CAC CGT GTC CAC CTT  (408-428) EphB4 AS-9 CTT CAG GGT CTTGAT TGC CAC (1929-1949) EphB4 AS-10 ATG GAG GCC TCG CTC AGA AA(1980-1999) Ephb4 AS-11 CAT GCC CAC GAG CTG GAT GAC (2138-2158)

TABLE 7 Inhibition of EphB4 Gene Expression by EphB4 RNAi probes PercentInhibition reduction of EphB4 in RNAi EphB4 RNAi sequence Expressionviability  1  446 aaattggaaactgctgatctg  466  2  447aattggaaactgctgatctga  467 +++ 70  3  453 aaactgctgatctgaagtggg  473++++ 70  4  454 aactgctgatctgaagtgggt  474 +++ 80  5  854aatgtcaagacgctgcgtctg  874 +++ 65  6  467 aagtgggtgacattccctcag  487 +35  7  848 aaggtgaatgtcaagacgctg  868 ++ 50  8  698aaggagaccttcaccgtcttc  718 +++ 75  9  959 aaaaagtgcgcccagctgact  979 +40 10 1247 aatagccactctaacaccatt 1267 ++ 50 11 1259aacaccattggatcagccgtc 1279 ++ 50 12 1652 aatgtcaccactgaccgagag 1672 + 3513 1784 aaataccatgagaagggcgcc 1804 +++ 65 14 1832 aagacgtcagaaaaccgggca1852 + 30 15 1938 aacatcacagccagacccaac   19 ++ 50 16 2069aagcagagcaatgggagagaa 2089 ++++ 75 17 2078 aatgggagagaagcagaatat 2098+++ 65 18 2088 aagcagaatattcggacaaac 2108 +++ 70 19 2094aatattcggacaaacacggac 2114 ++ 40 20 2105 aaacacggacagtatctcatc 2125 ++50 21 2106 aacacggacagtatctcatcg 2126 + 35 22 2197 aaaagagatcgatgtctccta2217 +++ 65 23 2174 aatgaggctgtgagggaattt 2194 ++ 50 24 2166aagaccctaatgaggctgtga 2186 ++ 50 25 2198 aaagagatcgatgtctcctac 2218 +++55 26 2199 aagagatcgatgtctcctacg 2219 +++ 70 27 2229aagaggtgattggtgcaggtg 2249 + 33 28 2222 aagattgaagaggtgattggt 2242 + 3029 2429 aacagcatgcccgtcatgatt 2449 ++ 40 30 2291 aagaaggagagctgtgtggca2311 +++ 50 31 2294 aaggagagctgtgtggcaatc 2314 +++ 60 32 2311aatcaagaccctgaagggtgg 2331 +++ 70 33 2497 aaacgacggacagttcacagt 2517 +35 34 2498 aacgacggacagttcacagtc 2518 + 40 35 2609 aacatcctagtcaacagcaac2629 ++ 50 36 2621 aacagcaacctcgtctgcaaa 2641 + 35 37 2678aactcttccgatcccacctac 2698 ++ 50 38 2640 aagtgtctgactttggccttt 2660 +++70 39 2627 aacctcgtctgcaaagtgtct 2647 ++ 50 40 2639aaagtgtctgactttggcctt 2659 + 25 41 2852 aatcaggacgtgatcaatgcc 2872 +++75 42 2716 aaagattcccatccgatggac 2736 ++ 50 43 2717aagattcccatccgatggact 2737 ++ 60 44 2762 aagttcacttccgccagtgat 2782 +++70 45 3142 aagatacgaagaaagtttcgc 3162 ++ 50 46 3136aatgggaagatacgaagaaag 3156 +++ 66 47 2867 aatgccattgaacaggactac 2887 483029 aaaatcgtggcccgggagaat 3049 + 33 49 3254 aaaatcttggccagtgtccag 3274++ 50 50 3255 aaatcttggccagtgtccagc 3275 +++ 75 51 3150aagaaagtttcgcagccgctg 3170 +++ 80 52 3251 aagaaaatcttggccagtgtc 3271 ++50 53 3256 aatcttggccagtgtccagca 3276 ++ 50 Additional RNAi probesdescribed in the specification Eph B4 50 gagacccugcugaacacaauu Eph B4472 ggugaaugucaagacgcuguu Eph B4 1562 caucacagccagacccaacuu siRNA 2303cucuuccgaucccaccuacuu Eph B4 2302 cucuuccgaucccaccuacuu

EXAMPLE 9 Inhibition of Ephrin B2 Gene Expression by Ephrin B2 AntisenseProbes and RNAi Probes

KS SLK, a cell line expressing endogenous high level of ephrin B2. Cellviability was tested using fixed dose of each oligonuceotide (5 UM).Gene expression downregulation was done using cell line 293 engineeredto stably express full-length ephrin B2. KS SLK expressing EphrinB2 werealso used to test the viability in response to RNAi probes tested at thefixed dose of 50 mM. Protein expression levels were measured using 293cells stably expressing full-length EphrinB2, in cell lysates after 24hr treatment with fixed 50 nM of RNAi probes.

The results on Ephrin B2 antisense probes were summarized below in Table8. The results on Ephrin B2 RNAi probes were summarized below in Table9. TABLE 8 Ephrin B2 antisense ODNs. Percent reduction Inhibition Codingin of Ephrin B2 sequence region viability Expression Ephrin AS-51 TCAGAC CTT GTA GTA AAT GT (983-1002) 35 ++ Ephrin AS-50 TCG CCG GGC TCT GCGGGG GC (963-982) 50 +++ Ephrin AS-49 ATC TCC TGG ACG ATG TAC AC(943-962) 45 ++ Ephrin AS-48 CGG GTG CCC GTA GTC CCC GC (923-942) 35 ++Ephrin AS-47 TGA CCT TCT CGT AGT GAG GG (903-922) 40 +++ Ephrin AS-46CAG AAG ACG CTG TCC GCA GT (883-902) 40 ++ Ephrin AS-45 CCT TAG CGG GATGAT AAT GT (863-882) 35 ++ Ephrin AS-44 CAC TGG GCT CTG AGC CGT TG(843-862) 60 +++ Ephrin AS-43 TTC TTG CCG CTG CGC TTG GG (823-842) 40 ++Ephrin AS-42 TGT GGC CAG TGT GCT GAG CG (803-822) 40 ++ Ephrin AS-41 ACAGCG TGG TCG TGT GCT GC (783-802) 70 +++ Ephrin AS-40 GGC GAG TGC TTC CTGTGT CT (763-782) 80 ++++ Ephrin AS-39 CCT CCG GTA CTT CAG CAA GA(743-762) 50 +++ Ephrin AS-38 GGA CCA CCA GCG TGA TGA TG (723-742) 60+++ Ephrin AS-37 ATG ACG ATG AAG ATG ATG CA (703-722) 70 +++ EphrinAS-36 TCC TGA AGC AAT CCC TGC AA (683-702) 60 +++ Ephrin AS-35 ATA AGGCCA CTT CGG AAC CG (663-682) 45 ++ Ephrin AS-34 AGG ATG TTG TTC CCC GAATG (643-662) 50 +++ Ephrin AS-33 TCC GGC GCT GTT GCC GTC TG (623-642) 75+++ Ephrin AS-32 TGC TAG AAC CTG GAT TTG GT (603-622) 60 +++ EphrinAS-31 TTT ACA AAG GGA CTT GTT GT (583-602) 66 +++ Ephrin AS-30 CGA ACTTCT TCC ATT TGT AC (563-582) 50 ++ Ephrin AS-29 CAG CTT CTA GTT CTG GACGT (543-562) 50 +++ Ephrin AS-28 CTT GTT GGA TCT TTA TTC CT (523-542) 70+++ Ephrin AS-27 GGT TGA TCC AGC AGA ACT TG (503-522) 65 +++ EphrinAS-26 CAT CTT GTC CAA CTT TCA TG (483-502) 75 +++ Ephrin AS-25 AGG ATCTTC ATG GCT CTT GT (463-482) 60 +++ Ephrin AS-24 CTG GCA CAC CCC TCC CTCCT (443-462) 45 ++ Ephrin AS-23 GGT TAT CCA GOC CCT CCA AA (423-442) 50+++ Ephrin AS-22 GAC CCA TTT GAT GTA GAT AT (403-422) 50 +++ EphrinAS-21 AAT GTA ATA ATC TTT GTT CT (383-402) 60 +++ Ephrin AS-20 TCT GAAATT CTA GAC CCC AG (363-382) 60 +++ Ephrin AS-19 AGO TTA GGG CTG AAT TCTTG (343-362) 75 +++ Ephrin AS-18 AAA CTT GAT GGT GAA TTT GA (323-342) 60+++ Ephrin AS-17 TAT CTT GGT CTG GTT TGG CA (303-322) 50 ++ Ephrin AS-16CAG TTG AGG AGA GGG GTA TT (283-302) 40 ++ Ephrin AS-15 TTC CTT CTT AATAGT GCA TC (263-282) 66 +++ Ephrin AS-14 TGT CTG CTT GGT CTT TAT CA(243-262) 70 ++++ Ephrin AS-13 ACC ATA TAA ACT TTA TAA TA (223-242) 50+++ Ephrin AS-12 TTC ATA CTG GCC AAC AGT TT (203-222) 50 +++ EphrinAS-11 TAG AGT CCA CTT TGG GGC AA (183-202) 70 ++++ Ephrin AS-10 ATA ATATCC AAT TTG TCT CC (163-182) 70 ++++ Ephrin AS-9 TAT CTG TGG GTA TAG TACCA (143-162) 80 ++++ Ephrin AS-8 GTC CTT GTC CAG GTA GAA AT (123-142) 60+++ Ephrin AS-7 TTG GAG TTC GAG GAA TTC CA (103-122) 80 ++++ Ephrin AS-6ATA GAT AGG CTC TAA AAC TA  (83-102) 70 +++ Ephrin AS-5 TCG ATT TGG AAATCG CAG TT  (63-82) 50 +++ Ephrin AS-4 CTG CAT AAA ACC ATC AAA AC (43-62) 80 ++++ Ephrin AS-3 ACC CCA GCA GTA CTT CCA CA  (23-42) 85 ++++Ephrin AS-2 CGO AGT CCC TTC TCA CAG CC   (3-22) 70 +++ Ephrin AS-1 GAGTCC CTT CTC ACA GCC AT   (1-20) 80 ++++

TABLE 9 Ephrin B2 RNAi probes. Percent Inhibition RNAi Sequence andhomology reduction in of Ephrin B2 RNAi with other human genes.viability Expression no. 189 aactgcgatttccaaatcgat 109 80 ++++ 1 141aactccaaatttctacctgga 161 70 ++++ 2 148 aatttctacctggacaaggac 168 75 +++3 147 aaatttctacctggacaagga 167 60 +++ 4 163 aaggactggtactatacccac 18340 ++ 5 217 aagtggactctaaaactgttg 237 80 ++++ 6 229aaactgttggccagtatgaat 249 50 +++ 7 228 aaaactgttggccagtatgaa 248 80 ++++8 274 aagaccaagcagacagatgca 294 80 ++++ 11 273 aaagaccaagcagacagatgc 29360 +++ 12 363 aagtttcaagaattcagccct 383 66 +++ 13 370aagaattcagccctaacctct 390 50 +++ 14 373 aattcagccctaacctctggg 393 50 +++15 324 aactgtgccaaaccagaccaa 344 90 ++++ 16 440 aaatgggtctttggagggcct460 80 ++++ 17 501 aagatcctcatgaaagttgga 521 50 +++ 18 513aaagttggacaagatgcaagt 533 50 +++ 19 491 aagagccatgaagatcctcat 511 50 +++20 514 aagttggacaagatgcaagtt 534 66 +++ 21 523 aagatgcaagttctgctggat 54366 +++ 22 530 aagttctgctggatcaaccag 550 50 +++ 23 545aaccaggaataaagatccaac 565 35 ++ 24 555 aaagatccaacaagacgtcca 575 40 ++25 556 aagatccaacaagacgtccag 576 60 +++ 26 563 aacaagacgtccagaactaga 58360 +++ 27 566 aagacgtccagaactagaagc 586 70 +++ 28 593aaatggaagaagttcgacaac 613 75 ++++ 29 577 aactagaagctggtacaaatg 597 66+++ 30 594 aatggaagaagttcgacaaca 614 35 ++ 31 583 aagctggtacaaatggaagaa603 50 +++ 32 611 aacaagtccctttgtaaaacc 631 70 ++++ 33 599aagaagttcgacaacaagtcc 619 70 ++++ 34 602 aagttcgacaacaagtccctt 622 80++++ 35 626 aaaaccaaatccaggttctag 646 50 +++ 36 627aaaccaaatccaggttctagc 647 25 + 37 628 aaccaaatccaggttctagca 648 30 ++ 38632 aaatccaggttctagcacaga 652 60 +++ 39 633 aatccaggttctagcacagac 653 40++ 40 678 aacaacatcctcggttccgaa 698 30 ++ 41 681 aacatcctcggttccgaagtg701 20 + 42 697 aagtggccttatttgcaggga 717 30 ++ 43 Additional Ephrin B2RNAI probes described in the specification GCAGACAGAUGCACUAUUAUU ephrinB2 264 CUGCGAUUUCCAAAUCGAUUU ephrin B2 63 GGACUGGUACUAUACCCACUU ephrinB2 137

EXAMPLE 10 EphB4 Antibodies Inhibit Tumor Ggrowth

FIG. 57 shows results on comparison of EphB4 monoclonal antibodies byG250 and in Pull-down assay.

FIG. 58 shows that EphB4 antibodies, in the presence of matrigel andgrowth factors, inhibit the in vivo tumor growth of SCC15 cells.

BalbC nude mice were injected subcutaneously with 2.5×10⁶ viable tumorcells SCC15 is a head and neck squamous cell carcinoma line. Tumors wereinitiated in nu/nu mice by injecting 2.5-5×10⁶ cells premixed withmatrigel and Growth factors, and Ab's subcutaneously to initiate tumorxenografts. Mice were opened 14 days after injections. SCC15 is a headand neck squamous cell carcinoma line, B 16 is a melanoma cell line, andMCF-7 is a breast carcinoma line. The responses of tumors to thesetreatments were compared to control treated mice, which receive PBSinjections. Animals were observed daily for tumor growth andsubcutaneous tumors were measured using a caliper every 2 days.Antibodies #1 and #23 showed significant regression of SCC15 tumor sizecompared to control, especially with no additional growth factor added.

FIG. 59 shows that EphB4 antibodies cause apoptosis, necrosis anddecreased angiogenesis in SCC 15, head and neck carcinoma tumor type.

Angiogenesis was assessed by CD-3 1 inumunohistochemistry. Tumor tissuesections from treated and untreated mice were stained for CD31.Apoptosis was assessed by immunohistochemistry TUNNEL, and proliferationby BrdU assay. Following surgical removal, tumors were immediatelysliced into 2 mm serial sections and embedded in paraffm using standardprocedures. Paraffin embedded tissue were sectioned at 5 μm, the waxremoved and the tissue rehydrated. The rehydrated tissues were microwaveirradiated in antigen retreival solution. Slides were rinsed in PBS, andTUNNEL reaction mixture (Terminal deoxynucleotidyl transferase andflourescein labeled nucleotide solution), and BrdU were added in ahumidity chamber completely shielded from light. The TUNNEL and BrdUreaction mixture were then removed, slides were rinsed andanti-flourescein antibody conjugated with horseradish peroxidase wasadded. After incubation and rinsing, 3,3′diaminobenzidine was added.Masson's Trichrome and Hematoxylin and Eosin were also used to stain theslides to visualize morphology. Masson's Trichrome allows to visualizenecrosis and fibrosis. The tumor gets blood support from tumor/skin,muscle boundary. As tumor grows, inner regions get depleted ofnutrients. This leads to necrosis (cell death), preferably at the tumorcenter. After cells die, (tumor) tissue gets replaced with fibroblastictissue. Slides were visualized under 20-fold magnification with digitalimages acquired. A different morphology was obtained on SCC tumors witheach antibody administered. Ab #1 showed an increase in necrosis andfibrosis but not apoptosis. Ab #23 showed an increase in apoptosis,necrosis and fibrosis and a decrease in vessel infiltration. Ab #35showed an increase in necrosis and fibrosis, and a small increase inapoptosis and a decrease in vessel infiltration. Ab #79 showed a largeincrease in apoptosis, and necrossis and fibrosis. Ab #91 showed nochange in apoptosis but an increase in proliferation. And Ab #138 showedan increase in apoptosis, necrosis, fibrosis and a decrease inproliferation and vessel infiltration. Tumors treated with control PBSdisplayed abundant tumor density and a robust angiogenic response.Tumors treated with EphB4 antibodies displayed a decrease in tumor celldensity and a marked inhibition of tumor angiogenesis in regions withviable tumor cells, as well as tumor necrosis and apoptosis.

FIG. 60 shows that systemic administration of antibodies on xenograftsleads to tumor regression in SCC15 tumor xenografts.

Alternate day treatment with EphB4 monoclonal antibody or an equalvolume of PBS as control were initiated on day 4, after the tumors haveestablished, and continued for 14 days. Systemic administration wasadministered either IP or SC with no significant difference. All theexperiments were carried out in a double-blind manner to eliminateinvestigator bias. Mice were sacrificed at the conclusion of the twoweek treatment period. Tumors were harvested immediately postmortem andfixed and processed for immunohistochemistry. EphB4 antibodies 40 mg perkg body weight were administered. Treatment with EphB4 antibodysignificantly inhibited human SCC tumor growth compared withcontrol-treated mice (p<0.05). Treatment with EphB4 antibodysignificantly inhibited tumor weight compared with control-treated mice(p<0.05).

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated byreference in their entirety as if each individual publication or patentwas specifically and individually indicated to be incorporated byreference.

While specific embodiments of the subject invention have been discussed,the above specification is illustrative and not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of this specification and the claims below. The fullscope of the invention should be determined by reference to the claims,along with their full scope of equivalents, and the specification, alongwith such variations.

1. An isolated soluble polypeptide comprising an amino acid sequence ofan extracellular domain of an EphB4 protein, wherein the EphB4polypeptide is a monomer and binds specifically to an Ephrin B2polypeptide.
 2. The soluble polypeptide of claim 1, comprising aglobular domain of an EphB4 protein.
 3. The soluble polypeptide of claim1, comprising a sequence at least 90% identical to residues 1-522 of theamino acid sequence defined by FIG.
 65. 4. The soluble polypeptide ofclaim 1, comprising a sequence at least 90% identical to residues 1-412of the amino acid sequence defined by FIG.
 65. 5. The solublepolypeptide of claim 1, comprising a sequence at least 90% identical toresidues 1-312 of the amino acid sequence defined by FIG.
 65. 6. Thesoluble polypeptide of claim 1, comprising a sequence defined by FIG. 1or
 2. 7. The soluble polypeptide of claim 1, wherein the solublepolypeptide inhibits the interaction between Ephrin B2 and EphB4.
 8. Thesoluble polypeptide of claim 1, wherein the soluble polypeptide inhibitsclustering of Ephrin B2 or EphB4.
 9. The soluble polypeptide of claim 1,wherein the soluble polypeptide inhibits phosphorylation of Ephrin B2 orEphB4.
 10. The soluble polypeptide of claim 1, wherein the solublepolypeptide is a fusion protein.
 11. The soluble polypeptide of claim 1,wherein the soluble polypeptide comprises one or more modified aminoacid residues.
 12. An isolated soluble polypeptide comprising an aminoacid sequence of an extracellular domain of an Ephrin B2 protein,wherein the soluble Ephrin B2 polypeptide is a monomer and binds withhigh affinity to an EphB4 polypeptide.
 13. The soluble polypeptide ofclaim 12, comprising residues 1-225 of the amino acid sequence definedby FIG.
 66. 14. The soluble polypeptide of claim 12, comprising asequence defined by FIG.
 3. 15. The soluble polypeptide of claim 12,wherein the soluble polypeptide inhibits the interaction between EphrinB2 and EphB4.
 16. The soluble polypeptide of claim 12, wherein thesoluble polypeptide inhibits clustering of Ephrin B2 or EphB4.
 17. Thesoluble polypeptide of claim 12, wherein the soluble polypeptideinhibits phosphorylation of Ephrin B2 or EphB4.
 18. The solublepolypeptide of claim 12, wherein the soluble polypeptide is a fusionprotein.
 19. The soluble polypeptide of claim 12, wherein the solublepolypeptide comprises one or more modified amino acid residues.
 20. Apharmaceutical composition comprising the soluble polypeptide of claim1, and a pharmaceutically acceptable carrier.
 21. A pharmaceuticalcomposition comprising the soluble polypeptide of claim 12, and apharmaceutically acceptable carrier.
 22. A cosmetic compositioncomprising the soluble polypeptide of claim 1, and a pharmaceuticallyacceptable carrier.
 23. A cosmetic composition comprising the solublepolypeptide of claim 12, and a pharmaceutically acceptable carrier.23-33. (canceled)
 34. A method of inhibiting signaling through EphrinB2/EphB4 pathway in a cell, comprising contacting the cell with aneffective amount of a soluble polypeptide of claim
 1. 35. A method ofinhibiting signaling through Ephrin B2/EphB4 pathway in a cell,comprising contacting the cell with an effective amount of a solublepolypeptide of claim
 12. 36. (canceled)
 37. A method of reducing thegrowth rate of a tumor, comprising administering an amount of apolypeptide agent sufficient to reduce the growth rate of the tumor,wherein the polypeptide agent is selected from the group consisting of:(a) a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; and (b)a soluble polypeptide comprising an amino acid sequence of anextraceliular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide.
 38. The method of claim 37, wherein the tumor comprisescells expressing a higher level of EphB4 and/or EphrinB2 thannoncancerous cells of a comparable tissue.
 39. A method for treating apatient suffering from a cancer, comprising administering to the patienta polypeptide agent selected from the group consisting of: (a) a solublepolypeptide comprising an amino acid sequence of an extracellular domainof an EphB4 protein, wherein the EphB4 polypeptide is a monomer andbinds specifically to an Ephrin B2 polypeptide; and (b) a solublepolypeptide comprising an amino acid sequence of an extracellular domainof an Ephrin B2 protein, wherein the soluble Ephrin B2 polypeptide is amonomer and binds with high affinity to an EphB4 polypeptide.
 40. Themethod of claim 39, wherein the cancer comprises cancer cells expressingEphrinB2 and/or EphB4 at a higher level than noncancerous cells of acomparable tissue.
 41. The method of claim 39, wherein the cancer ismetastatic cancer.
 42. The method of claim 39, wherein the tumor isselected from the group consisting of colon carcinoma, breast tumor,mesothelioma, prostate tumor, squamous cell carcinoma, Kaposi sarcoma,and leukemia.
 43. The method of claim 39, wherein the cancer is anangiogenesis-dependent cancer.
 44. The method of claim 39, wherein thecancer is an angiogenesis-independent cancer. 45-48. (canceled)
 49. Themethod of claim 39, further including administering at least oneadditional anti-cancer chemotherapeutic agent that inhibits cancer cellsin an additive or synergistic manner with the polypeptide agent.
 50. Amethod of inhibiting angiogenesis, comprising contacting a cell anamount of a polypeptide agent sufficient to inhibit angiogenesis,wherein the polypeptide agent is selected from the group consisting of:(a) a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; and (b)a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide.
 51. The method of claim 50, wherein the cell expressesEphB4 or Ephrin B2.
 52. A method for treating a patient suffering froman angiogenesis-associated disease, comprising administering to thepatient a polypeptide agent selected from the group consisting of: (a) asoluble polypeptide comprising an amino acid sequence of anextracellular domain of an EphB4 protein, wherein the EphB4 polypeptideis a monomer and binds specifically to an Ephrin B2 polypeptide; and (b)a soluble polypeptide comprising an amino acid sequence of anextracellular domain of an Ephrin B2 protein, wherein the soluble EphrinB2 polypeptide is a monomer and binds with high affinity to an EphB4polypeptide.
 53. (canceled)
 54. The method of claim 52, wherein theangiogenesis-associated disease is selected from the group consisting ofangiogenesis-dependent cancer, benign tumors, inflammatory disorders,chronic articular rheumatism and psoriasis, ocular angiogenic diseases,Osler-Webber Syndrome, myocardial angiogenesis, plaqueneovascularization, telangiectasia, hemophiliac joints, angiofibroma,wound granulation, wound healing, telangiectasia psoriasis scleroderma,pyogenic granuloma, cororany collaterals, ischemic limb angiogenesis,rubeosis, arthritis, diabetic neovascularization, fractures,vasculogenesis, and hematopoiesis.
 55. The method of claim 52, furtherincluding administering at least one additional anti-angiogenesis agentthat inhibits angiogenesis in an additive or synergistic manner with thesoluble polypeptide. 56-61. (canceled)